[defcon65]

Where is your water meter? Why not just abandon all the pipe under the slab and retrofit new copper? Anybody that can work on Porsches should be able to solder copper pipe, and it's not that expensive at your Home Depot or whatever. $7000 to coat pipes with some epoxy goo sounds way too expensive for a three-bedroom, two bath slab house. You can install new 1/2" copper in the walls by removing the baseboards, cutting back the drywall, notching out the studs at the bottom and placing the new lines 1" apart in nail-in pipe clamps. (I'm assuming your house has wood studs) Be sure to install steel stud-guards over the notches so they don't get hit with nails when you re-attach the baseboards.
I'm not a huge fan of plastic water pipes, but most of the installed examples I've seen have been botched home-owner jobs. I'm sure it works fine if installed correctly, it's just that none of the plumbers I hire even touch the stuff.
That's my take on it; others may feel different. I've rehabbed close to three hundred houses in Western Illinois and never pay more than about $1500 for a complete copper repiping. All the parts and supplies for a house like you describe should cost less than $300, including solder, flux, cleaning tools, a pipe cutter and MAPP torch kit.
The key to successful pipe-sweating is to clean the mating surfaces very shiny, use plenty of flux and heat them till they glow dark red or the flame turns greenish, then feed the solder in all the way around the joint and wipe the drip with a denim rag.
Try it, you'll feel like a pro!

Good Luck,

Joe