Adding 10 speed bar ends on a 7 speed bike

I'm not sure, but I suspect the indexing is different (due to different cog spacing) between 7 speed and 10 speed, so I don't think the 10 speed bar end shifters would work for you in index mode.

If the shifters have a "friction mode" then you could probably use that.  Just means that you'd have to decide how far to move the shifter rather than just clicking it--but that's the way everybody used to shift before index shifting was invented.

Have you had a mechanic take a look at your old shifters?  And/or replaced your cables?  Might be a fixable problem rather than needing total replacement.

I had a 1988 Cannodnale SR400. I stripped it of everything except the frame and front derailleur. I built is up with a 9 speed mountain bike flatbar, trigger shifters, compact cranks, chain, mtn brake levers, road brake calipers, and cassette. I spent a lot of time researching component compatability. A former racer and mechanical engineer with a PhD from MIT told me it was OK to install a 130mm hub in the 126mm rear dropout spacing.

Everything must be the same speed system and manufacturer compatability. SRAM and Shimano OK Shimano and Campy BAD. Your 7 speed rear hub is NOT compatable with 9 or 10 speed systems. You are looking at the cost of a brand new components package. Look for a good used bike with 9 or 10 speed drivetrain. Ebay may have the shift levers you need.

Yeah, I had them looked at, and the mechanic basically said they are near the end of their use.  I am more than likely going to take it to a different LBS, as I've moved, to see if I get another answer.  

Thanks for the help.  I am hoping all I need to do is try the friction mode for bar ends, but will probably be looking for a new ride in the future...

I'm not sure what your definition of pricey is, but you can still get new 8 speed Ultegra bar ends on Amazon and run them in friction mode.

Edit: just looked on ebay--I'm not sure where those 7 speed shifters will end up, but so far they seem reasonable.

Does your bike have a cassette, or a freewheel system? Sheldon Brown has info on changing a 7-sp system to 8 or 9.... If you were able to go this route, then you could use a used 8 or 9-spd set of bar cons that someone no longer needs, and not be limited to friction-shifting

http://sheldonbrown.com/k7.html

Yeah, found some for $30, DEFINITELY doable, considering the price of a full groupo

Three things to note:

1) As previously described, your 7 speed hub won't work with an 8-9-10 speed cassette...unless, that is, you replace the freehub body and axel and re-space, or get really whacky and try something like 8 of 9 on 7 or 9 of 10 on 7 (click and scroll about 3/4 of the way down for a description by Captain Bike).

2) Shimano 8 speed bar end shifters will work with your 7 speed cassette - Shimano left the spacing (and cable pull) per shift largely the same when they went from 7 to 8 speeds, with the extra freehub body width making up the difference between the two standards.

3) Be careful about any thoughts of large scale upgrades with your current frame.  Shimano 7 speed rear hubs were 126mm on axle, 8+ speed are 130.  You can squeeze the wider hub into the narrower frame, but with an aluminum bike, you'll ramp up the fatigue quickly (unlike steel bikes, you can't cold set aluminum), and you may run into difficulties properly centering your rear wheel.