Front Rack mounts
 

I have an older bike that has clamps to mount a front rack. It is a cheap Performance Bike rack.
I would like to get a better rack that mounts with screws on the fork. Would it be easier / cheaper to get a new threaded fork,
o have my LBS drill mounting points?

The cheapest and easiest would be to use P-clamps; it is commonly done and works well. If installed properly the clamps are barely noticeable.

Your LBS should not drill mounting holes in your current fork blades and is hopefully not foolish enough to offer to do so. Fork blade threaded mounts are brazed on bosses that are thick enough to have proper thread depth and strong enough to reenforce the fork blade where they are applied So, either get a replacement fork with the proper bosses or, as dsbrantjr recommended, get P-clamps and use them.

You can look into Surly LHT or Crosscheck forks, they are well-threaded for front racks.

http://surlybikes.com/parts/category/forks

But if you're dealing with an older bike that you don't want to put money into, clamps should work just fine.

Sent op a message re a Long Haul trucker fork.

If the fork has fender eyes at the dropout, you'll have no problem using P-clips for the upper mount . You can also use 4 P-clips , but if you do so make sure the lower ones are as low as possible, and oriented with the screw below the blade, so they can't slip down and gravity keeps them from rotating.

only if your shop does custom bike frame repairs,the 'hole', must be reinforced, by brazing, then repainting ,
so fails on the easy - cheap criteria.
better using some of the external mid fork mounting suggestions above..

I wonder if the OP's bike is old enough to have a 1" steerer. If so, only the current Surly Cross Check forks will work as they are the only model available in both 1" and 1-1/8" threadless form with threaded mid-blade rack eyelets. http://surlybikes.com/parts/cross-check_fork

All other Surly forks are either 1-1/8" only or have no eyelets.