Just a suggestion, this thread may do beter in "General Planted Tank Disscussion
" forum or the "Equipment
As for tanks..I' not a fan of the pre-done kits, but I'll give you my list for usual tank/equipment buying.
If you have access to Petco they will have a $ per a gallon sale.. Dec 26 through mid January I believe? You can get a 20g long or tall for $20 + tax, or a 40g breeder (which I've been told is actually 43g) for $40+ tax.
For heater.. well its more expensive but I trust Eheim Jagar and use those in all my tanks except the picos, 75-125 watt heaters are about $25-30.
For filtration I've used a few things, AquaClear HOB filters, sponge filters with tetra whisper 10 air pump, and canister filters (sunsun (cheap but loud) and eheim (expensive but silent-you forget its there). Price range for these can be $30-100 depending on what you want.
If you plan on adding plants you can get cfl 6500k bulbs (9-14 watt) at a grocery or home improvement store for cheaper than "grow lights" (about $4-6 a bulb, and clamp on work lamps/reflectors for about $8-10 (2-4 lights and lamps depending on tank length). And either put lamps clamped to a shelf above the tank or get some cheap chain and a hook to hang them from the ceiling (makes it much easier to adjust height for lighting needs).
If you want a lid, I use Lexan polycarbonate from Home Depot (the thing acrylic they sell bows horribly, lexan does not), price varies depending on you tank dimensions probably $20-40 roughly. It can be cut with just about any saw (higher tooth count makes a better cut) or a razor or utility knife.
Substrate.. I use Tractor Supply co.s Black diamond blasting 'sand' 20/40 grit or -60 grit. Its $8 for a 50lb bag, 3 bags ($24) have filled: 2g, 3g, 6g, 7g, 12g long, 20g long, and 55g. If you want light colored sand substrate look at play or pool filter sands.
The petco sale is for tetra tanks which don't have the most seller silicone work. If you are willing to spend a few extra $ and about an hour you can get: rubbing alcohol, a straight razor, and GE I door and window clear silicone and scrape off old silicone with razor, ru down area with the alcohol, then re-silicone the tank. Did with with a 10g and 20g long, had and no issues with the tank. You can read up or find videos about redoing silicone or setting up tanks from scratch (the tetra tank has rim/trim so you don't need tape to keep glass pieces together as you would with a completely DIY rimless glass tank siliconing).