I don't like Tempur-Pedic "foam rubber" mattresses for the reason you stated. Instead, I want a regular firm or extra-firm interspring mattress but with a layer of memory foam in the top layer of the mattress. That's called a Euro-top or pillow-top mattress. The custom mattress makers will probably make you one, but if an ordinary 60x80 queen mattress will fit on your bedframe, then you can get one for a lot less money from a discount outfit such as SamsClub.com
That's what I did. Serta Euro-top firm mattress with multiple foam and other layers totaling about 2" thick on top of the springs. My exact mattress is no longer on the Sam's website, but the one in this link is very similar - except I think mine cost closer to $500.
SertaŽ Perfect SleeperŽ Edgebrooke Cushion Firm Eurotop Mattress - Queen - Sam's Club
Here's the details of the Eurotop layers, with cover and springs plus 10 layers of foam and other stuff, including one layer of memory foam.
SertaŽ Perfect SleeperŽ Edgebrooke Eurotop Mattress
$400 if you order it online, but that includes delivery to your house by a freight company, and they will haul off your old mattress if you don't want it. The truck driver and his swamper expect a tip, so plan on it.
But only $350 if you go to the store with your membership card and pick it up yourself.
You can buy that same Serta mattress at any mattress store, but it will probably have a different name. And of course the mattress salesman will tell you that their version is much better and therefore costs twice as much as the one Sam's sells. If his mouth is moving, he's probably handing you a load of bullpukey.
We don't have Costco here yet, but they have similar deals on normal-size (not RV size) name-brand mattresses. Here's a Sealy Posture-Pedic ultra-firm with 3.5" of foam of various types - including a layer of memory foam - between the quilted top and the springs:
Birchmere Ultra Firm Queen Mattress
Yeah, that one costs more than the one from Sam's, but maybe a Posture-Pedic really is better than a Perfect Sleeper?