What if i want offers on a firearm? And list multiples?

The rules state i must list a price. I don't want to do anything improper but i have multiple items i want to list so can i list all my handguns together and my long guns together and can i put a dollar for the price wanting best offer? OR do i need to list individually and or put an actual asking price on each firearm (i really don't know what some are worth)? Thank you