I reckon to set up an 8' tank with a decent filter, heaters and lights would be about $1500 plus a stand plus your fish. This is assuming $800 for the tank (for a new or newish one).
I built my 6' that our aro is in (he's now maybe 45-50cm, nearly ready for a bigger tank), got the glass for free so tank cost just a tube of silicon, but stand/paint/fittings cost $350, gear (filter (AR1200), lights, heaters) $320. The filter is a bit marginal, really need two.
For something like an 8', I would go for an aquis 2400 (or equiv other brand) and another smaller canister. Our aro tends to freak out if there is too much light, so a pair of 4' twin flouros should work well ($100 each) and you'd want maybe 3 or 4 300w heaters at say $30, plus protectors (when they get big, they can smash glass heaters).
You could do it all on a budget if you DIY'd, but for a turn-key system, the above would be the way I'd do it.