@Natasha388 I have an ancient sofa bed that was very cheap, £250, when I bought it 23 years ago from a cheap catalogue high street shop. It's a pull out one, metal frame & a 'trampoline' type base, - strong fabric suspended by springs. The mattress included is only 1-2" thick, but one the ONE time I slept on it about 4 years ago it was VERY comfortable! (Even in my mid 50s!) - More comfortable than many a cheap mattress I've slept on!
I've read reviews from local 'rival' hosts with clic-clack sofa beds... - LOTS of complaints about them being hard & uncomfortable!
Go for the pull out bed, but not the solid base sort, the TRAMPOLINE sort! I figure it's the springs round the edge which allow 'give' which make it comfortable! - And if you added a memory foam topper, it would be even more comfy! (I have CHEAP 3" memory foam toppers on my bed & one guest bed, bought off the internet - £30 single, $40 double. They are supremely comfortable; guests & I say so!)
That said, would the springs suspending the trampoline stand up to regular use? Might it depend on whether ALL your guests would use the sofa bed, or just occasional ones, i.e. 2 mates not wanting to share a double bed, or a 2 bed/4 guest house being occasionally used to sleep 6 via the sofa bed in the living room?