IRA's & Mutual Funds
Honestly, the first thing you should invest in is a
good
set of used irons, 3-PW. I definatly reccomend used because 1) their cheaper, 2) in the winter, their dead cheap, 3) 90% of the time, the resale is equilivant.
Start with a nice cavity back set. They're much more forgiving and you'll see drastic improvements with your shots. I reccomend the Taylormade RAC OS2s. They can be easily found for under $275 used. I'd shy away from anything overly expensive because honestly, at this point, you definately won't be able to tell the difference.
Secondly, a great quality putter. You take the most strokes with it and should reign confidence the minute you pull it out of the bag.
Third, get yourself a nice wedge. Used cleveland wedges fetch a very fair price (~$25) and will get your short game going.
Lastly, a nice driver can be found around $100. Doesn't need to be overly fancy, just enough to get it 'out there.' This is frankly where I'd spend the least amount of dough.
Oh, and ProV1's are a waste of money for high handicapped players.