What did you do to your bike where you need a "new drivetrain" for it?
What is your LBS suggesting that he will be replacing the current drivetrain with?
Really. Just WHAT did you do to your bike which has resulted in the need for what must be an extreme makeover?
IMO, your LBS's projected cost is akin to a person coming in with a FLAT TIRE and the guy saying you need a new wheelset which will cost (because they are on sale!) you a mere $900 (tires, tubes, rim strip, CF wheels, cassette) ... they'll throw in the labor for free, but they'll charge you the necessary sales tax!!!
Get thee to an REI & attend one of their bicycle maintenance clinics.
OR, buy one of ZINN's books or the BICYCLING MAGAZINE's maintenance book + some tools on an as needed basis (most of the tools you will need can be generic METRIC tools ... generally, only the Cassette lock ring tool, possibly the BB tool, and a chain tool will be bike specific).
If you didn't trash your bike, then you probably only need one-or-two things ...
AND, one thing may simply be a can of 3-in-1
) light machine oil ... and, the other is possibly a can of Liquid Wrench
if you have really neglected your bike's maintenance. That will set you back about $5 for the two + time + some paper towels.
I do NOT know what kind of drivetrain you have on your bike ... but, a new chain will set you back $15-$30 depending on how you source it (eBay can be your BEST FRIEND especially if there is only one bike shop within 20 miles of where you live
) ... a chain tool will be $20 +/- ... get on which can handle a 9-speed chain at the very least ...
A chain tool which can handle a 10-speed chain can handle a 9-/8-/7-/single-speed chain
In other words, if you did not crash
your bike then should probably try lubing it ...
When you have the time, elaborate on what you think needs to be "replaced"-or-fixed ... AND/OR post some pics of the parts which are supposedly not functional-or-not-functioning ....
Because a new BB & crank should cost you less than $100 ... much less ...
AND, new derailleurs (presuming it isn't a bike with internal gearing) do not need to cost you more than $100.