A custom rifle does not have to be expensive or too pretty to hunt. A simple restocking can turn a factory rifle into a custom number. Stocks are available in utility grade through $$$$ and also include sythetics.
While I don't consider sight changes or butt plate changes to be "custom guns" that is also a way to "customize" your rifle. The 405 WCF I mentioned started out as a 30 Gov't carbine. It now carried rifle wood, a long barrel, and an aperture rear sight. Side by side with an original 1895 rifle, you would be hard pressed to tell them apart. Other of my rifles, much easier. For example, the Ruger M77/22 that has a Winchester M52 barrel. None of my rilfes have had fancy wood or engraving but all have been at home being carried about. I just try to change them to fit my needs.