The rack and bag are easy. Just about any rack should fit and you needn't go too expensive on it. The bags usually attach with velcro and are interchangeable. Topeak makes a slightly different system that fits on their racks and aren't interchangeable. Their racks work with any bag but their bags don't work with just any rack.

Fenders, on the other hand, are more problematic. Unless you want to change the front fork (not in keeping with your wishes to keep it cheap), you'll probably want to use a fender that's made for suspension fork. I use the SKS Shockblade. It works well with the shock and doesn't require funky mounting.

The rear is more difficult because of the v-brakes. The rack will do a lot of the work that you need to keep water off your back but it won't do anything to keep the glop off your drivetrain. Conventional fenders offer more coverage but they might not fit between the v-brakes. I've found that I can route something like the SKS Adventure fender over the v-brakes and then attach a lower section of the fender (use the part of the front fender) to extend it. Like this


This is what the whole bike looks like



Make sure you attach the end of the fender to the rack or it will hit the tire and buzz annoyingly.