I'm planning to do the same thing too.
Do a search and see. There are a few sources for them. Almost any dealer who repairs tubs should be able to get them too.
The biggest problem I can see as a non-spa professional is identifing the correct jet size. Funny thing, when I asked my dealer about using other Waterway jets - she said nothing else would fit. Luckily for me, NJDave is an Artesian dealer and repairs other brands and he's not too far from me ... I just have to get to him!