Hi Snagged,
You will also need a bedframe to go under the foundation and a mattress protector to go over the mattress but if your maximum price is $600 for just the mattress and foundation and there is no way to go any higher and you are OK with the idea that for some people the mattresses you are considering may only last you a matter of months (which I wouldn’t consider to be good value in any budget range) or that you may not sleep well on them even when they are new (overstock doesn’t provide good guidance that can help you match your specific needs and preferences in a mattress) and you are also OK with not being able to return them if they don’t turn out to be a suitable match for you then it may be worthwhile considering them.
I would personally go in a different direction though.
You could purchase a wire grid platform foundation for under $100 (see the foundation post here) which would leave you about $500 for your mattress. At these budget ranges … the more you can put into your mattress the better.
If you look at some of the Dreamfoam models here you will see some innerspring mattresses including 3 pocket coil pillowtop options (one with polyfoam, one with memory foam, and one with latex) and the budget saver that uses a Bonnell coil (but isn’t a pillowtop) that would all be better quality choices than the mattresses you are considering. Keep in mind that if you order any of these mattresses from the Dreamfoam site there is an additional 10% discount.
There are also several other foam (non innerspring) options that are in the same or lower budget ranges that would be well worth considering as well that would also use better quality and more durable materials than the mattresses you are considering.
There are also several other options in the previous post I linked with the lower budget options from Ikea that would be inside your budget range as well.
There may also be some local options that are close to you that would make better quality/value choices as well that would give you the chance to try the mattress in person so that you don’t get “stuck” with a mattress that isn’t suitable for you that you don’t sleep well on and can’t return.
Phoenix