I'm not a buggy racer but I've been racing for about 30 years and am Chairman of the Milton Keynes Club. I can't offer advice on type of buggy but...
My view on this is the idea of 8.5 / 7.5 brushless motors is crazy - far too fast for a beginner. I'd suggest you consider a cheap Ansmann brushed motor, something like a Clash 23 turn brushed motor (RRP £7.95) with a cheap / 2nd hand brushed ESC (you can get a LRP Quantum Pro Sport ESC for about £10 off fleabay). With motors, the lower the number, the faster the impact speed when you crash (and you will)
Regarding your affinity for Tamiya, if you have a local indoor club (and seeing as winter's approaching fast) it may be worth finding out if they run a Tamiya Mini class. The Tamiya M03/M05 is durable and cheap to run but provides great fun for all. At the moment our club gets about as many mini racers as it does touring cars. The kits cost around £90 (shop around for bargains), use cheap Ni-MH cells (about £18 each) and as easy to build, drive and cheap to maintain.
HTH
Dave