I've been through this same dilema myself and found no good solutions, so I made one.
I wanted a wheeled bag, with a shoulder strap, and easy-access to the laptop so I could get it out for security at the airport. But all of the combo SLR/laptop bags I've seen have been either wheeled pilot cases or backpacks; I couldn't even find a wheeled backpack. The wheels are important to me because with all my camera gear and laptop gear in it, the bag gets too heavy to lug around the airport on my shoulders.
Since I couldn't find one that met my needs and didn't cost $200-$300, I decided to make one of my own. I started with a sub-$40 American Tourister wheeled carry-on case from
Walmart. The case has the standard zip front, two external zip compartments, and a laptop compartment that's accesible from the outside via a zipped flap on the side. It also comes with a removable laptop sleeve, though I don't use that - my 15" laptop doesn't fit in it.
I then purchased a 4" slab furniture-grade foam rubber from a local foam store, and cut out custom compartments for my camera gear. This filled the main compartment of the bag perfectly. An additional 1" slab of foam went into the back of the bag, between the lining and the retractable handle, to protect the laptop from hitting the handle. I finished up with a pair of 1" U-bolts, drilled through the top of the back to create snap points for a shoulder strap.
When finished, the bags layers are like so:
4" slab of foam with camera gear
1" empty space where teh laptop slides in from the side compartment
Bottom nylon lining of the bag
1" foam slab
Retractable handle
I took some pics of the bag as I was assembling it, but I lost them when I reformatted the memory card before downloading. But I'll take a few some time in the future.
The overall effect is something like a poor man's Pelican. The total cost of the bag and materials was less than $50, but I think it will hold up as well as a $200 bag, and it has all of the features that I wanted in a bag. It's also easy to re-configure - all I have to do is buy another slab of 4" foam and cut new compartments in it, and I'll have a completely different bag.