I had purchased an AXO Weekender gear bag for my son last year, and it performed well enough that I bought another one for myself.
There are very few bags in the 'under-$50' range and there are even fewer that are what can be called full-sized bags.
This bag is extremely large and is nearly a square-shape. However, it still qualifies as a 'standard size' for airline baggage and doesn't incur an oversize fee. It has a nice web handle that velcros together, as well as a longer shoulder strap.
The zippered end compartment easily holds my size 11 boots, while the main compartment holds my helmet, neck brace, pressure suit-style chest protector, knee guards, elbow guards, pants, jerseys and still has lots of room for other items you might want to toss in.
Being a relatively budget-priced bag means it isn't the thickest of nylons, but ours have held together quite well. The zipper pulls are metal, and the bottom is vented. There is also a vinyl-covered stiffener for the bottom, which serves to keep smaller items from falling out thru the vent holes
For the weekend rider, this bag can't be beat, and if and when it falls apart, it is cheap enough to purchase another.