Depends on your area and how bad some one is hurting for money. Tanks in my area go for 50cents per gallon used. This is 10 gallons to 90 gallon tanks.
The biggest reason for this, is because the local Pet Co runs a sale every year on brand new tanks 1$ per gallon. (again 10 to 90 gallon tanks only)
Stands. Good luck on that. Most are way over priced to begin with new. In my opinion you can build a stronger, sturdier stand cheaper than buying one. This holds very true if you already have most of the nails and glue and stain left over from another project!