It is not uncommon for sellers to hold on to the item until the personal check clears. It might take a few extra days, but some don't mind when using checks.
You can also ship the firearm yourself. UPS hubs take firearms from individuals being mailed to a FFL. Your local store front can tell you where it is or look it up online.
(Don't get UPS (brown truck guys) mixed up with the United States Postal Service, USPS does not take handguns.)
I always ask for a copy of the receiving dealers FFL be emailed to me. Then I use
https://fflezcheck.atf.gov/fflezcheck/ to make sure they are legitimate.
However, your local gun shop or other FFL may be able to get you a better or comparable deal to ship. It is definitely worth a few minutes to call and check.
You can find a list of FFLs in your area by using one of the search engines designed for that.
https://www.gunbroker.com/ffl/searchforffl.aspxhttps://grabagun.com/ffl-locatorThis link might also help if you decide to ship yourself.
https://www.ups.com/us/en/help-center/packaging-and-supplies/special-care-shipments/firearms.pageIf you do some basic research ahead of time, you can get in close proximity to the actual shipping cost and add that extra fee as a condition for sale.
i.e. Sale price + $20 shipping.
Good luck with your sale.