Affordable solution to make bunks more comfortable?

[95jersey]

The bunks in my RV are ok, but not great. Is there a cheap way to make them more comfortable without buying a $300 mattress? Mattress topper? Foam underneath?

I have odd sizes 30x74 and 42x74 so it is not easy to find ready made toppers. Also, I see standard poly fill, foam, gel foam, and memory foam. I am looking for the most comfort for under $100 per bed.

[DutchmenSport]

How about getting an air mattress (or a couple of those blow up recliner swim things you lay on when swimming), and put them UNDER your current mattress. At least, give it a try. If the cheap-o swim ones help, then maybe you can invest in a more suitable blow-up mattress, camping mattress. If you don't want to use your existing mattress, toss it out and get a nice Coleman blow up air mattress used for tent camping. Some of them are like, 18 inches thick! Some are only 4 inches ... those might work well UNDER your current mattress to make it more suitable. Just a thought?????