Selling raw vintage ... what's a good price?

[wdwfan]

First of all, I'm not sure if this is in the right place or not. If it's not, please move it to where it needs to go. Thanks.

Here's my questions...
I'm fairly new into vintage (been collecting since August) and have been trying to sell off some of my vintage doubles as well as other cards/lots from years I don't like. But I'm having trouble, and I'm looking for help from vintage experts.

What's a good percentage to sell cards at? I'm talking 1975 and older. I checked ebay, and it seems most of the big boys list Vg-Ex to Ex stuff at 30% of BV or higher. I know that's ebay, and you can't get that on places like BO, SCF and Net54.

I started listing at 25% of BV with no takers and then dropped below that a little bit. Now I'm down to 20% of BV and still can't get any takers. So what am I missing?

I'll use one of my cards as an example. It's a 1966 Topps Hank Aaron (BV $120). I started it at $40, got no takers, dropped it to $30 and got no takers and am now down to $28 (less if you buy it as part of the lot it's in). So I can't move it for 20% or less than BV.

So what's a good percentage? Or am I missing another variable that I'm not aware of. Sometimes I wonder if it's because I'm not selling big names. But in the case of the Aaron, that's not the case. So not sure what the deal is. Any help would be appreciated because I'm setting up in a show in Dallas in about a month and need to know what to price all my vintage cards at. Thanks.