[jb67]

Post a picture of the card here and it will help.
Not many PSA 7.5's have been sold so your price will be based more on eye-appeal. If your 7.5 is centered you will certainly get more than 414.22 which is what the last one sold for. Also you could very easily sell it here on this board versus Ebay. Good luck with your sale. Post a picture and you will get a much better idea of the price.
From VCP. Here are the last 3 that sold in PSA 7.5

3/19/15 eBay Image probstein123 d***d 31 $414.22
9/17/14 eBay Image cowboyzfan1970 u***0 1 $350.00
8/11/13 eBay Image glibersher t***w 29 $207.50

VCP PSA 8 Prices (Average Price: $1,799.88)
9/22/16 eBay Auction | Image pwcc_auctions d***r 29 $1,429.00
9/22/16 eBay Auction | Image pwcc_auctions m***g 19 $1,550.00
9/9/16 eBay Auction | Image doug19672004 s***x 21 $1,533.51
8/21/16 eBay Listing | Image 420blackwidow o***s Best Offer $2,100.00
8/18/16 eBay Auction | Image probstein123 e***e 26 $2,550.00
8/15/16 eBay Auction | Image probstein123 h***a 50 $1,730.00
8/15/16 eBay Auction | Image probstein123 h***a 31 $1,325.18
8/11/16 Huggins & Scott Auction | Image 14 $2,031.50