Suspension is the place that you don't want to skimp.
I'm not a fan of spacers, but they do well enough for some. An adjustable Blaster or Banshee axle would be the ticket.
As for up front, you have a few options:
1. Buy used and save money but potentially lose out on performance. Shocks need to be valved and sprung for the rider weight, riding style, experience, and what arms they'll be used with. If you get shocks that are meant for a rider that weighs 100lbs differently than you, for arms with a different leverage ratio, and for a different terrain, you probably won't like what you end up with.
2. Buy new and build it as one unit. This addresses all the above issues, but costs more.
3. Buy used arms and new shocks. This is a median between #1 and #2.
My recommendation is to save up and do it once. Skimping will leave you unhappy and potentially buying twice. Go with some good long travel arms and run some Fox Floats. Theyre lightweight, easy to dial in for a wide variety of applications, and don't really cost that much for what you get in terms of quality and performance. Comfort is through the roof. Don't forget that long travel arms require long travel shocks.
Later on, get some 4/1 rims and a longer swingarm. Don't go too long, just go long enough to keep the front end down.