If you want the best of the best of the best you can get an ARS-7010 rack. It's about $100 per level with heat panels installed, you would just need a temperature controller like a VE-100 (for less than $100). If you plan on expanding you can get a few levels of an ARS-7030 hybrid rack, they sell for about $200 per level and have three tubs per level, so about $66 per tub. That's actually how I started out and eventually stacked on more levels.
http://arscaging.com/ars7030.html
If you want the cheapest of the cheap you can buy a wire rack shelving system and use plastic totes with holes drilled in the sides. You would still need to buy heat tape for a hotspot and a thermostat to control the heat.
You can also build it out of melamine but don't get it wet or it will swell up and get ruined.
Beware of cheap racks that are totally made of plastic and can be tipped over by a dog or child.
Freedom Breeder is a close second to ARS but some say the build quality isn't what it should be for the price. Personally I haven't compared it side by side to ARS so I'm not too sure about this comment. I have ARS rodent racks and the Freedom Breeder rodent racks seem to have more options like screened covers on tubs, recessed water nozzles, etc... Personally I'm totally sold on all ARS racks and am building a professional outfit as my business grows. I want something that I can hand down to my grandkids and will last for generations.
Honestly I think the best thing to do would be to go to a big retile show like NARBC and look at all the racks on display. Give them a shake to see how stable they are, pull out the tubs to see how they slide. A personal inspection will give you more than we can ever say on this forum.