Welcome to TPT!
If you read through some journals in the Journal forum, some people keep track of that info in there... (I did for my 90gal).
Of course, the initial startup is the biggest cost... until you decide to upgrade this, that or the other down the line.
I'm setting up a low tech 29gal right now, and so far my expenses are along these lines:
$20 used tank
$90 stand (new)
$100 Hagen Glo 1x24 watt T5HO (new)
$20 used Flourite black substrate
$100 used Eheim Ecco 2234 filter
$50 filter media, Purigen, thermometer, Prime, other misc supplies
And probably another $300 to plant and stock it.
Maintenance costs are minimal, mostly just fish food and Prime when I run low. Electricity is probably the most expensive monthly cost... but running T5/T5HO fixtures makes the most efficient use of wattage.
Unless I get the bug to change something... or something breaks and needs replacing...