Having run a gallery, I agree that talking to the curator or gallery director is best. Different regions have different popular standards and they will advise what they are looking for. But, don't be surprised if they aren't willing to speculate the price for you. Some galleries have a strict "you set it" policy and they won't even make a suggestion.
However, having worked in galleries in three different regions of the country now, here are some trends I've noticed. People who buy photos don't spend on photos. The most popular price points are $50-$125, regardless of size. Strange, I know. Buyers also tend to gravitate toward ones that have an air of mystery, like when they are printed on aluminum or canvas. I think it makes them feels like they are getting something more fancy than it is, somehow, like it's *almost* a painting. If you want to sell, don't go big. Unless the region you are showing in is filled with McMansions, don't make anything bigger than 16x20. People have limited wall real estate for art, and they buy based on that.
As for mechanical advice, put a secure wire on the back. I freaking hate it when artists bring in a frame with glass and the thinnest, cheapest wire that isn't even knotted to the screw-eye that's barely secured in the wood of the frame. I have yelled at artists for it before. If you need help, go to Michael's have them do it for $5 and watch them so you can learn.
There are different types of hinging tape if you try that method (I use the self adhesive not the gummed).
Filmoplast P-90 is the bomb-diggity of hinging tapes for photos. Linen tape and the like is for heavier duty materials.
Lastly, congrats on being included in a gallery show!! That's a super big achievement that many artists never come to know, so be proud and keep putting your work out there.