Re: If you had $5000 to get started wrenching what would you buy?

A little late to the party, but if you're going RWD, go all in.  Get a V8 pony car, or like Unkeludo said, a non mustang fox body.

May i suggest a 4th gen, LS powered, 6 speed Camero.  I found one with 120K on it, original owner, for 5K.  I've been DDing it for almost 2 years.  Clutch slave needed replacement last fall, which was a motherfucker to replace with the exhaust being in the way, but I got it done in the driveway.  i throw a set of studded snows on it in winter, and as long as there's not a foot of snow down, it gets around fine.

borrow a friends tools.  You'll be thrilled at the performance/$ spent, and almost miata fuel mileage.  i generally get 23 commuting and upper 20's on the highway.  You can store a full set of 275/40/17 slicks in it on your way to HPDE, along with a pop up, and about 200 lbs of tools/gear.

We also have a 5th gen Camero SS, but I like driving this better.  It's lighter and just as quick.  I'm sure it's not as fast around a road course, but it's still pretty fast.

Silent But Deadly Racing-  Ricky Bobby's Laughing Clown Malt Liquor Thunderbird , Datsun 510, 87 Mustang (The Race Team Formerly Known as Prince), 72 Pinto Squire waggy, Parnelli Jones 67 Galaxie, Turbo Coupe Surf wagon.(The Surfin Bird), Squatting Dogs In Tracksuits,  Space Pants!  Roy Fuckin Kent and The tribute to a tribute to a tribute THUNDERBIRD!