Need help with Fuel injectors

I think I have a bad injector or two on my 1990 Maxima GXE with the 3.0 SOHC motor...

I am going to try and change the bad injectors out myself...anybody tried this? It doesn't look that difficult except for finding out if my motor uses the blue or black striped injectors...

ALSO...what sites have the cheapest injectors...I need to conserve cash...somebody mentioned getting some online for $75...WHERE??


thanks