After lunch, when I came back to my bicycle, my 10mm Avenir combination coil lock won't open. A bike shop sold me some oil, but that didn't help.
So now my bicycle is stuck 4-miles from my house and I need to cut off the lock.
Local bike shops weren't able to provide this service and a local locksmith wants over $100 to cut the lock. So I have to figure out my own solution.
I don't want to go out and purchase multiple expensive tools and perform trial and error to see what works. I need advice from people who've actually cut coil locks from bicycles. I constantly hear how easy it is for a thief to snap off one of these things. Somehow I imagine, its more complicated for an amateur to actually remove these locks.
What tool should I buy from a hardware store to remove my lock?
Please also share any techniques as well.

I think you have already answered how it could be done (7th line), but as this is a forum where people don't normally want to have their locks removed except by themselves, will leave for you to hack out the solution.

My hunch is that bolt cutters would work, would rather know for sure before spending $30. I'm concerned that bolt cutters won't handle braided cable as well as a solid metal bolt. But it people are uncomfortable saying so, I can understand

I've thought about a manual hacksaw, but that would seem to take a long time.

Call a cop over for assistance ~

About 15 minutes with a hacksaw ought to do it, cut next to the lock. Bolt cutter faster but likely need at least a 24" for the jaw opening, maybe bigger.

Before buying any tools I would recommend checking a tool rental store for bolt cutters or a battery powered reciprocating saw. If your bike is near an electrical outlet, a right angle grinder would do the job.

A cable shear that will cut it like butter will cost as much as the locksmith, the question is how much future use would you have for the shears?

A follow up to DMadro's post, there are battery right angle grinders, with a cut off blade it would take no time to get through.

I posted this on your other thread- buy long handled bolt cutters from homedpot(keep your teciept) cut off lock take bolt cutters back next day for refund.job well done for free.

A lot of youtube videos show that turning a big can of compressed air upside down, spraying it where the lock interface is, and then hitting it with something like a sledge hammer will do the trick. That's if you can brace the lock on something solid like a concrete sidewalk.

It's not fake. I've seen a master coil combination lock broken like this.

So long as it is sharp you shouldn't have a problem.

You con't need big "one pull" cable shears. You can do this job with a set of decent full size side cutters. You'll just need to cut through a few strands at a time and worry it through. Or you can use a hacksaw. But again it'll be annoying because it'll keep catching on he strands so use a very light pressure and medium speed. A finer tooth blade would also be a good idea. And either of these tools would have a good place in your tool kit at home after the job is done.

The can they used is not actually compressed air. It's a rapid evaporation pressurizing liquid. Turning it upside down pushes the liquid out instead of the gaseous form of the same stuff. The liquid then evaporates REALLY fast. In doing so it draws the heat out of the metal of the lock. Use enough of it and you pull the metal down to a very low temperature similar to that of "dry ice". At that point the metal becomes more brittle than at normal temperatures.

The same product is also sold in electronics stores as "Freeze Spray" or something of the sort. It's the same stuff but you don't need to turn the can over. If you do then it just shoots out the gas.

The success of this would be based on how cold you can get the metal that is inside the plastic protective outer jacket. It would be best to remove the jacket plastic first and use the liquid form of "air in a can" directly on the metal.

If a trip to Oakland or Berkley isn't too much trouble they have tool libraries there.

Perhaps one would have a battery powered angle grinder

OR

an angle grinder + inverter and you have a car you can use.

This might be the time to invest in a pair of quality cable and housing cutters, which can nip their way through the cable lock a little bit at a time. Then you'll keep them and use them for maintaining the bike.

The alternative is to buy bolt cutters which you might not use again.

call a tow truck or a thief

Pedros cable cutters. Takes maybe three or four snips tops if it's 10mm cable. Other brands of bicycle cable cutters will work, but it helps if it's the same style as the Pedros.

Edit: A cordless dremel with a cutoff wheel does it just as quick.

Bolt cutters. We used them in the refinery to cut Master padlocks.

Before going crazy cutting the lock, I would try an aresol penetrating oil like Liquid Wrench. A good spray can comes with a thin tube to direct the spray deep into the lock.

Good Luck.

Thanks everyone! With all of the debate and some complicated suggested solutions, let me explained what worked:
A cheap $5 hacksaw from home depot and 10 minutes of moderate elbow-grease, cutting right where the solid lock joins the cable.
I also called the non-emergency police number and asked them for advice - since I was in the open cutting off my bicycle lock.
They gave me their blessing. Remember this, if it ever happens to you. If I knew this, I would have walked to the nearest home improvement store and would have been back in business in 30-minutes with no stress.

P.S. I tried some oil first, didn't help.

That won't work if the OP has any ethics.

A battery powered dremel tool with a thin cutting blade will do the job in about 30 seconds.