From my own experiences, after looking for a good camera bag for long hikes, is to adapt something better suited to cycling to hold camera gear. The problem with photo backpacks and stuff, is even the lowepro bags designed for more outdoorsy pursuits, still fall short on the comfort and performance.
For cycling, I gutted an old camera bag and reused the padded dividers. I throw this in my Timbuk2 bag and use it like their own camera bag inserts. It works fantasticly, and is much more comfortable than any camera bag in a similar price range. They even have a full waterproof lining on the fabric, so light rains and road spray will keep everything dry without having to take a nylon cover on and off all the time.
I know you mentioned not wanting a messenger bag/sling, but if you're cycling, make sure to try one designed for cycling, instead of for fashion. I can get everything in and out of the main compartment without opening it, after swinging it around in front of me. No need to take it off a shoulder, or undo anything. The 'hidden' pocket is fantastic for keeping filters, lens caps, etc, as it can be accessed without even swinging it around front. For heavier loads, or if you're on a more aggressive position on a road bike, it comes with a hip stabilizing strap. For cycling, these are much more comfortable to me than most normal backpacks, and a lot of cycling oriented backpacks.
Another issue with conventional photo bags and a lot of backpacks, is the top hitting your helmet, and pushing your head forward-- bad in a crash, bad for visibility. VERY bad on a road bike. I've tried a couple decent photo bags, and when fitted properly they'll hit my helmet. When lowered down on my back to avoid this, the suspension isn't balanced, and it will cause me lower back pain, and sore shoulders.
The Timbuk 2 medium bags (size I have and recommend) go for $100-$120 retail, but can be often had on special for about $60.
Classic Messenger Bag 2014 - Timbuk2 Bags
Here's their own camera insert:
Snoop Camera Insert | Camera Bag Insert | Camera Case - Timbuk2 Bags
I just reused padded dividers from another photo bag ($8 at a thrift shop) which leaves more room for other gear.
EDIT: Also, this insert system gets transfered into m canyoneering pack (42 liters) into the sleeping bag compartment for day hikes, climbing trips, etc. It also works in my 75L pack for backpacking, but it takes up a lot of space, so I usually just attatch my toploading camera bag to the back of my large pack.
---------- Post added 02-15-14 at 12:36 PM ----------
Also, forgot to mention, Timbuk2 makes some nice photo bags as well, and all their backpacks are designed with cyclists in mind. A bit more $$$ than your price range, but they run specials frequently.