Congratulations!
First of all congrats on the new purchase!
You can do all the BPU mods with some friends, they're easy.
Just make sure you get some good jacks (hydraulic ones) and some jack stands. You don't want your car falling on you
Get a GReddy BCC,
Boost gauge, Downpipe ($250 from PMImporting), Exhaust, intake kit, EGR block-off kit ($10 from Mohd on the mkiv.com list), swap ALL the fluids in the car (10W30 mobil 1 for the motor, STOCK (demand the stuff that CAME with the Supra, not the stuff they put in Camrys and Celicas) Toyota fluids for the transmission and differential and radiator). You probably want a boost controller, too... everyone likes the Blitz DSBC. The HKS EVC EZ is really cheap and simple, too. Or you could be a cheapass like me and do the VSV mod and just boost 18psi all the time.
If you add in a fuel controller (probably should get a shop to tune this one...) you can probably hit over 400rwhp pretty easily.
I'd say the hardest thing to do is the downpipe, since you have to get under the car and wrench like hell at the downpipe bolts (which have probably rusted up a little bit). Nothing a little muscle and some breaker bars won't handle...
Also, get better tires (I like Bridgestone Potenzas, 255/40/17 and 285/40/17) and maybe front and rear strut tower bars. Get the TRD front bar, it's a badass unit.
I'm in SoCal so I can't help you with shops in Florida, but I know there are at least a few high-profile Supra shops there.