I have a trek kaitai 2011 with less than 500 miles on it. Awesome bike I love it even more since I put 700x45 tires on it. My local bike shop wants about 250 to set it up with disc breaks (since I need new rims for them as well)
But...
My coworker just offered me 400 for the bike!

So do I keep it and add 250$ worth of upgrades or do I sell it and spend another 300 to get a 8.2 or something similar!! I'm so stuck and can't make a decision.

Lastly if anyone knows where I can get set up with decent rims and disc breaks for less then wod help my decision...Thanks!!

So first off I have to say that disk brakes are not that much better than rim brakes except in extreme cases. I would say DO NOT spend $250 for the upgrade, a %40 upgrade (of the cost of the bike) will not give you a bike that is %40 better, maybe %4.

The 8.2 looks to be right on par with the kaitai, save some very minor component changes and 700c over 650.

If you have money you want to spend, upgrade the components on you kaitai, starting w/ the shifters. Bicycles are more fun to ride when they shift properly. Having quality shifters and drive train components is the best way to insure that once a bike is setup, it will hold that tune and perform as designed.

I would also replace the suspension fork with a rigid one. that suntour is very heavy and is probably sapping energy from your stroke. If you are riding off road alot and feel a suspension fork is necessary, then put a good one on there.

If you dont ride w/clipless pedals yet I suggest you experiment with them while you have some cash to spend.

also all the little stuff you may need may be a better use of your cash instead of the disk brakes, ie seatbag, tubes, tools, patch kit, pump (frame and floor), lights, helmet, good lock.......

So you're within $50.00? Get the new bike.

Its a Suspension fork Hybrid

2011 Trek Gary Fisher Kaitai - BikePedia

so a Dual sport 8.something will be the similar type with the Sus Fork

FX 7. 12345Etc, will be a lighter bike just because it is not built around that fork, type.

local here would do a consignment or trade in.

There is another option: Spend nothing at all and use the perfectly functional v-brakes the bike came with.

What do you hope to gain by swapping out your current brakes for discs? You may note I didn't use the word "upgrade", as disc brakes have pros and cons when compared to other braking systems.

That was my thought. I am a big proponent of keeping what you have until you are ready for a big upgrade. Less than 500 miles is barely broken in. IMO, the 8.2 isn't an upgrade at all over what you have. A DOWNGRADE in most respects, if you look closely at the specs. 8.3 is mostly just a lateral move. Basically, an updated version of the kaitai but with mechanical disc brakes instead of V brakes, which is maybe an upgrade, but only a very slight one. Trading in a 3 year old NOS bike for a brand new entry level trail bike doesn't make much sense. IMO, you really aren't upgrading much until you get to the 8.5DS, which does have hydraulic discs, better fork, and upgraded 9 speed drivetrain, but that will cost you north of $1,000 retail.

Your co worker is smarter than you think. A basically new bike like that with upgraded tires for $400 that would retail for $660 today, new. (The DS 8.3). Any reason you feel you have to have disc breaks? FWIW, my son rides with a high school mountain biking team, and close the half the team still uses bikes with V Breaks, and they race single track. I know V Brakes are on the way out, and in a few years, only legacy bikes and entry level hybrids will have them, but for now, they work fairly well. You can always upgrade pads to something like Kool Stop pads for little money.

I agree with the comments above. Unless there is a reason why your current bike is not working, leave it as is and keep saving until you wear it out and/or are ready for a real upgrade.

And if braking performance is an issue, in addition to upgrading pads, you could always upgrade your V Brakes. Something like Deore XT, which was for serious mountain bikers just a few years ago is available now not very much money.

+1 You can upgrade to top of the line v-brakes for a small fraction of the cost of discs and enjoy better braking than you would have with entry level mechanical disc brakes. You would also make your bike lighter by a bit instead of about a pound heavier