Like I said it's super old so there are tons and tons of videos and forum posts across the web about it. I am pretty sure there are a couple threads around here someplace.
The cheapest nitro I would ever consider is the Hobao/Ofna Hyper 7, it's been around for a very long time so parts and upgrades can be found everywhere. https://www.absolutehobbyz.com/hobao-hyper-7-tq-rtr-w-h-2802turbo-engine-14kg-servos-2-4g-blue.html