Home wall padding?

Beginner climber here. I'm super stoked, but only get to go to rock on weekends with good weather, and no climbing gym within 2 hours. So I'm building my own, but since I don't have much experience, I don't know what is necessary as far as keeping myself from fracturing my spine on the concrete. Wall will be about 25 degrees, 10ft H X 8ft W. I don't really want to spend $600 on bouldering pads. I don't have any old mattresses nor do I want to use a random person's dirty mattress.  I haven't found any helpful tutorials on this. It's always "cheap DIY home wall" (with 4 $200 crash pads). Or "DIY padded floor" (with foam that costs $500). I've found some 6" thick furniture foam on Amazon. 8 ft for like $90-$100, but I'm not sure this will be enough if taking an uncontrolled fall from the top. The other thing I've found are 8ft long gymnastic pads for about $170, but again, they're only like 2" thick, and I don't think they would be fun to fall on. What the hell can I use that won't turn this already $500 build (including the holds) into $1000? I feel like I'm going crazy, why the hell is foam so expensive?

Used mattresses are going to be the best cheap option.

Buy a mattress case. They're $20. Or a tarp if you're that cheap. 

Then set up alerts for gymnastic padding. Every so often a gym or school gets rid of theirs and its usually dirt cheap. 

If you end up getting softer foam, you can add a layer of closed cell foam on top of it to spread out the impact. For example 12 inches of soft foam (2 layers of your 6inch stuff) with a layer of closed cell on top might work pretty well.

1" closed cell foam is pretty cheap even if bought new.

I personally just use crashpads, but my wall is only a 8x8 and I already had a bunch of pads.

We bought some of these and stuffed them full of used mattresses. They have lasted a year with no real damage. 

I DWS over a pool of the bitter tears I weep after consistently falling off the easiest Moonboard problems.

Also crashpads.

Creed Archibald wrote:

We bought some of these and stuffed them full of used mattresses. They have lasted a year with no real damage. 

Hm, these would make used mattresses look much better. Thanks for the suggestion. 

Although now that I think about it, maybe I should keep them dirty to motivate me not to fall