I love Sweetwater but they've cost me a lot over the years...
Some dealers offer special financing, usually through a store card, but with very rare exceptions it is a very expensive way to go. Some do have 0% for xxx months offers once or twice a year. Banks treat such purchases them as a personal (usually unsecured) loan and again you pay high interest so that's not generally a good idea. But, I have very limited and only local experience, so that may not be true everywhere. I had saved for a number of years before getting my first pair; the last two came about as a combination of a stock grant, unexpectedly large bonus, kids finally both graduated and on their own, and cancelled vacation that combined to open a window to a set of B-stock Salon2's. With the permission, and actually encouragement, of SWMBO!
As an aside, now and then I have wondered at a banking system that lets me finance a car at 0% for several years then go out and drive it around at great risk to all, but demands exorbitant interest rates for a pair of nice speakers that will sit safely in my media room.