The Manfrotto Pro 40 Messenger has been around for a few years, but that means it's usually pretty easy to find a great deal on this bag. For around $60, you can pick up a shoulder bag that will fit up to four lenses, a 13" laptop and a ton of smaller accessories. Besides all that space, the bag is also well-made, constructed with a water-repellent nylon. The dividers are adjustable, so you can fit a DSLR with a telephoto attached horizontally or with a shorter lens vertically. The shoulder strap is comfortable and there's a trolley strap for attaching to the top of your luggage.
The Manfrotto Pro certainly isn't a high-end canvas or leather messenger bag, but it also doesn't have that high-end price tag either. The biggest complaint is that the zippers don't offer split second access like velcro or flap closures do, though they tend to be more secure. If you do fully pack the bag with four lenses and a body, it will get heavy to carry compared to a backpack that distributes the weight between two shoulders. Despite those minor issues, the Manfrotto Pro offers more comfort and better organization than most other budget $50 bags, so if price is a top consideration, consider this bag from Manfrotto.