Craig's list prices vary all over the country. I had someone drive a huge dual wheel pickup from South of Chicago, to pick up a used 90 for $90.00. His local price for used was $300+. In the Detroit area I've seen ads for 100g+ tanks - free for the picking up. Even at that price it's been too far for me to bother.
I have an acquaintance who goes to pick up tanks and setups and then offers about half what the poster was asking, as he makes like he's heading out the door. It works for him.
As to Petco selling out fast, that is a factor of location. The last sale in my area, the first pile to accumulate was 40B size. Over a dozen before the sale started. They only sold two on the first Sunday. On another occasion, I had to go back every other day for two weeks to get ten 10g tanks. They came in, just not all at once.
I have an acquaintance who goes to pick up tanks and setups and then offers about half what the poster was asking, as he makes like he's heading out the door. It works for him.
As to Petco selling out fast, that is a factor of location. The last sale in my area, the first pile to accumulate was 40B size. Over a dozen before the sale started. They only sold two on the first Sunday. On another occasion, I had to go back every other day for two weeks to get ten 10g tanks. They came in, just not all at once.