@Tom937I believe we paid around $1,400 for our king mattress which is basically middle of the road in the king mattress world. Its not something you want to cut corners on in my opinion. Its a firmer mattress with a 3" foam top. Guests love the bed. Cheap mattresses sag and you end up having to replace them sooner.
We looked into supplying a Sleep Number bed in our guesthouse as we have one and its the best bed we have ever owned. Being able to have a firm bed or soft bed on demand is a great feature. We may still go this route once we upgrade our own Sleep Number mattress and put the one we currently have in there. We are just unsure if guests will be receptive to this kind of bed.