Try http://www.aerotechdesigns.com/ for a reasonable priced jersey. I haven't tried them myself, but I have some of thier bibs, and they are great.
As for the spin bike, try and set it up so it is close to the set up of your bike. Some have more/better/finer adjustments than others, so you might not get it perfect. It help to get somebody to look at your position to help identify any that might need adjustment that would be better seen from off the bike.
Do you use the same shoes as on your bike? Are they clipless?