Like some of you, I reuse a lot of material.
When I tore out my home studio recently, I saved every piece of wood that was longer than 2".
And, glad I did. When I had to put cross braces in between studs to box out outlets, switches and the like, one needs a few 15" long 2x4's. Scraps are good for this. Why waste a new 2x4 when you can use scraps?
The stringers in my studio, now that I've move them up and shorted them from 12' down to 58", required that I double them up for strength. I got several 58" stringers out of each 12' stringer as I tore them down, one at a time.
Electrical wiring, well, I've reused a lot of the old stuff. Same for outlets, wire nuts, etc. I'll be buying new outlet covers and switch plates because instead of cheap plastic, I want brass. No big deal.
I've attached a picture of my old studio racks, before the tear out. There were four or five of these, I simply made properly sized 2x4 verticals, then attached rack rails to them. Instead of buying rack rails from a music store, I simply took a 7' high aluminum relay rack and cut it into 18U and 6U sections. 6U on top, 18U on bottom, so I could put a small cross brace between.
The rack rails, before mounting, are then cut lengthwise on my table saw, because then I get two rails for the price of one
There were threaded holes on both sides of the u-channel rails. Why not use both sides? this way, a 42U rack can be cut up to provide 84U of space!
This is just SOME of the cheapo stuff I've done here at home. Pro studio to follow...
Oh, one more thing, I buy 99% of my gear on e-bay now. I've ended up standardizing on equipment thats not exactly the latest and greatest, so e-bay is a good source for this stuff. Instead of repairing stuff, I actually have a small stockpile of "extra" TMD1000 tascam digital mixers because it was less costly. Same for the akai recorders. Spare boards too.
Thinking I'm clever, I took the proms out of one of
my Akai DR16, 16 ch hard disk recorders and put them into one of my Akai DR8, 8 ch hard disk recorders. Magically it boot up, and thought it was an akai DR16. 16 channels for free! See, the internals/processing part are identical, the difference between the units is the amount of A/D and D/A it has, as well as very minor changes on the faceplate. But the display, the processor, the amount of memory, are all identical. The motherboards inside even have the same part number.
To solve the "I'm now a 16ch recorder but only have 8 inputs" problem, I shoved in a 16-ch adat card (which is the standard in my studio), so the DR8's are now full-fledged 16 channel recorders. All at the cost of moving prom chips. Since I can copy prom chips with this little thing I have, I took the latest version of the OS from one of the DR16's and made enough pairs of proms for each of the four machines that didn't have that version. So now I have five DR16 recorders
Two look funny heh-heh
might get a kick out of my new stereo mic stand. It will be fairly permanent so I don't care about having the mics stuck there. The mics are suprisingly adjustable and I can tilt, swivel and offset the mics for a few options. 
Muhah hah hahh!