Won't a strap from any large duffle bag work? I'd check a luggage store. At worse case, you can hit REI and the internet and make one yourself using webbing. They might have replacement straps there too.
I have a Golite Peak and a newer Golite Jam. I'm looking to replace the Jam's shoulder straps with the much more comfortable IMO
I went a completely different route and got a guitar/electric bass strap and a couple of those carabiner clips. The straps are both made to be comfortable and able to handle a lot of weight. (typically the weakest part is the leather ends, but they're still rated at like 60ish lbs) I found not only was this more comfortable than my previous strap, but allows some "customization" if desired. You could get a simple black strap, or something else that stands out. Likewise, having a couple of guitar straps lying around, it cost me about $4 in clips and I had a "new" shoulder strap.
Cool! Clever idea. However, make sure that you got "real" carabiners, not overly cheap ones intended to be used only as keychains. I'd be concerned that they could probably bend/fail in quick order, causing a possible catastrophe. If you can bend it with your hand strength, it's probably not strong enough.
I definitely agree that the keychains are a horrible idea, although I'm not sure what your definition of "real" carabiners are. You can get them at the hardware store that have a weight/load rating, and similar to the leather ends on the guitar strap, you don't need anything too crazy. If your bass has the same amount of weight as a mountain climber and all of their gear facilitating real climbing carabiners, you need to take the kettlebells and dead body out of your bass bag.
Beyond the hardware store and mountain climber's store a sailor's accessory shop is a good source for carabiners and similar stuff.
You pretty much nailed it right there - if they have a weight rating, they're "real" - if they're on the endcap by the register at Kmart, I'd probably take a pass... I only mentioned it because I've seen photographs of a bass that was dropped because of the player's trust in a strap contraption that wasn't up to the job. I'll also mention that - if you use a strap - you should probably carry it over your shoulder with an arm snugging the bass to your body for support. Many bass bags have D-rings for attaching a strap, but they are just sewn into the fabric of the bag, and the bouncing/jouncing of being "worn" like a backpack (bad idea) can cause those stitches to fail. Not to mention that not all D-rings are welded; they may only be bent into shape.
Thank you Mark, for this PSA. I stopped using a shoulder strap on my bag for that very reason. They were sewn into the first layer of the bag and not welded, and the D ring BOTH started unbending/opening, AND the stitching was failing. I have also seen a number of players with the backpack straps not duck low enough when going through doorways. Too many scrolls have big chips out of them, or have been broken clean off, and it scares me to think about it. Look at that picture. The bass extends almost two feet above her head! Be careful my friends. Whatever your transportation method may be, your instrument is both very fragile, and less protected than a cello in a hard case. Act accordingly.
Dave Messina could whip you out a righteous one that will last into the next millenia for cheap coin, I bet!
I bought a neoprene padded luggage strap from amazon. It is incredible, cheap, and I will buy one for every case I ever own.