Jay H

I can't really answer your question about how much it would cost, but since your bike has to be fairly new (2008), you'd think they'd be able to give you a general ballpark figure since I'd assume they wouldn't run into anything insane like putting disc brakes on an old bike without the propert disc tabs, etc. Try some other bike shops or wait for somebody here with more info.

I've managed to survive all these years of being my own wrench by borrowing cable cutters or just having my bike shop cut them (they do it for free) since I don't own a specialized bike cable cutter. However, you can probably get away with cutting brake cable housing with a good die-cutter or wire cutters since the sheathing on brake cables is just a spiral metal sheath. Derailleur cables need the special tool since they use wire beads which will completely crumble if you try it with a standard wire cutter. At least I can cut brake housings myself and I do.

I have a cassette tool which is a pretty handy tool to have, whether you are installing new brakes and want to switch your cassette to a new disc brake compatible wheel. Consider that your cassette on your rear wheel is a wearable item and you'll have to replace them as well as your chain and/or jockey pulleys sooner or later, it's worth the $12 Shimano Cassette tool, me thinks.

You can get by without a torque wrench, although I have one, I don't use it too often, so long as you don't manhandle/gorilla things and you check the tension on occasion.. I've lived all these years. I have a couple of torque wrenchs, but honestly, I don't always use them and actually most of them were bought for my car's mechanicals.

As far as your LBS's attitude... With labor and all that, if you have to have the LBS do the brake swap, it might of been cheaper to just buy it from them if they will do the conversion for free, but it sounds like it's too late for you...

Jay