I'm not certain what radio you have (Stock or NAV), but in any case, I'd say the first thing to do is the PELKED1 capacitor upgrade. Members here helped me out with getting this done and believe me, the 20 minutes that it took to do were WELL worth the effort! Do it!
https://www.crossfireforum.org/forum...-buck-mod.html

If you have a NAV radio then get Rudy Compart's iPhone/iPod/Flash Drive upgrade done! Cost is about $230 and gives you control of the iDevice from the radio. Rudy (Accelerated Industries) is a treat to work with and many members here will atest to his skills (both technical and inter-personal).
https://www.crossfireforum.org/forum...adio-here.html

If you don't have a NAV radio (as was the case with me), you can purchase one online for under $200 and go from there). Total cost would be well under $550.

You mentioned a convertible. Consider the Quick Touch switch for your top (also from Rudy). Too, you might want to consider a wind resistictor (I personally like the ADAMESH from Great Britain) or some of the others. Finally, you may want to do K&N air filters, change out the cabin air filter, get a Eurocharged tune (we have a group in Southern Ontario that Bluecoupe (Steve) is organizing to do this with) and then get the following spare parts: steering stabilizer, crankshaft position sensor, some $5/quart oil on sale at Advanced Auto right now) and some Mann Fleece filters for your cupboard.

That should spend most of your $750, get you some great additions and the most appropriate spare parts. Each of them worthwhile. Oh, and get yourself to a local get together and introduce yourself. BTW, share everything that you learn!

That is what this forum and the members have taught me over the past 4 months!