This is something I saw on CL earlier this year. Kinda long, but I tend to agree with a lot of it.
Yes, I know you spent a bucket of cash to get yours, but this is RESALE. And it's craigslist....the BARGAIN-hunter's market. Aquariums/fish tanks do NOT hold a high resale value. Therefore, for those of you who are trying to sell USED aquariums on CL and NOT getting your (often) exorbitant asking prices - here's a simple, FAIR guide to pricing: And because many of you don't know or need to find out exactly what size your tank is, here's a calculator:
http://animal-world.com/encyclo/inform ation/calculate.htm AQUARIUMS: Glass If it's a year old or UNDER - $2.00 - $3.00 per gallon. If it's OVER a year old - $1.00 per gallon. Hexagons - $2.00 or less/gallon. BowFronts - $1.50 - $2.00 per gallon (depending on condition) AQUARIUMS: Acrylic If it's a year old or UNDER - $1.50 - $2.50 per gallon. If it's OVER a year old - $1.00 per gallon. Hexagons - $1.50 or less/gallon. BowFronts - $1.50 - $2.00 per gallon (depending on condition) STANDS & CANOPIES: $1.00 per gallon of aquarium the stand holds. (REAL wood - add another $.50 to $1.00 depending on CONDITION) $.50 - $.75 per gallon of aquarium the canopy covers. (REAL wood - add another $.50 to $1.00 depending on CONDITION) GLASS TOPS and PLASTIC HOODS: 25% - 40% of retail LIGHTING: WITH newer bulbs: Incandescent - $5.00 (usually only 10 gallons or less are incan's) Fluorescent - $10.00 per foot Compact Fluorescent - $20 - $30 per foot (based on condition of housing, cord) Halide & Specialty - 50% of retail for ballasts; you should buy NEW bulbs unless they are evidently lightly used. REALLY High-end Fluorescent lighting - 60% of retail W/O bulbs or OLD bulbs: Incandescent - Free Fluorescent - $7.00 per foot Compact Fluorescent - $15 - $20 per foot Halide & Specialty - 50% of retail for ballasts; you should buy NEW bulbs unless they are very evidently lightly used. REALLY High-end Fluorescent lighting - 40% of retail ACCESSORIES: Saltwater - i.e. - protein skimmers, powerheads, wave-makers, chillers, etc....50% - 65% of retail (UNDER 1 year of use) Saltwater - i.e. - protein skimmers, powerheads, wave-makers, chillers, etc....25% - 40% of retail (OVER 1 year of use)Freshwater - 25% of retail (regardless of age - very easily replaced) GRAVEL: Natural colors - .15 - .20 cents per pound (clean) Other colors - .05 cents per pound HEATERS: UNDER a year (of use) old - 50W - $2 100W - $4 150 - 200W - $6 250 - 300W - $10 OVER a year old - free (heaters aren't trustworthy enough after a year of use to justify $$) FILTERS - UNDER a year old - 50% of retail OVER a year old - 25% of retail THINGS TO CONSIDER: An empty aquarium is ONLY an aquarium. ***** ONLY when full of livestock (that is included in the sale) is a tank considered a SALT or FRESH aquarium. There is NO SUCH THING as an EMPTY saltwater or freshwater aquarium. It is JUST an aquarium. ****If you have the EQUIPMENT, ACCESSORIES and /or LIVESTOCK for a SALTWATER hobby, then it is a "SALTWATER AQUARIUM SET-UP." ****If you have the EQUIPMENT, ACCESSORIES and /or LIVESTOCK for a FRESHWATER hobby, then it is a "FRESHWATER AQUARIUM SET-UP." REHOMING LIVESTOCK: Check local prices before you buy someone's critters. Often, buying livestock from a private party is better - especially if they have had (it) for a while w/o problems. MISC.: Chips, cracks & leakage are all signs of wear and reduce the prices significantly. Water marks, discolorations, scratches (esp. on acrylic) and hard-water deposits are usually cosmetic. Because many can be removed with effort, they need not affect price. Accessories are always great to 'throw in' as a bonus when buying a tank, but pricing everything, stating 'will not separate' and expecting a quick sale - not good. Not many people are not going to use all YOUR stuff if they have other ideas for THEIR new tank. OK, so this is JUST a guide for SELLING your tank(s) and is intended to give a starting point for pricing it (them). I've sold MANY aquarium very quickly under these parameters. You should do well, too, if you don't get greedy. And buyers? There will be exceptional SET-UPS out there and what you ultimately pay will depend on you, but this (hopefully) gives you a 'ballpark' idea of what you can expect. Happy Fish-keeping, everyone!
R - Don't buy things at high prices that are used. 
