Triathlon - Forward seat post or New Seat, which first?

I am making some changes to my Raleigh Grand Prix to use it for tri riding, as I can't afford to purchase a new bike right now. I am picking up a set of aero bars from a friend for $25, and have about $100 left over. So, do I purchase a forward seat post or a new seat next? My current seat is very near the end of it useful life, but I can't afford a seat and seat post at this time, so which would be a better purchase now?

Also, if i get a forward seat post, can I use it for just regular road riding, not in the aero position, or am I going to have to switch back and forth between the two posts?

BTW, I am really new to the triathlon world, did my first one a few weeks ago and already planning on doing several next year though.

it depends on what is a higher priority for you, forward seat post will make you more aero, seat will only be more comfortable. Yes you might have to do some seatpost switching. You should train with the forward leading up to your tri's but if you are doing any road racing, off season training, or major group rides, you probably should use the other seat post. the forward seat post is less stable, and lowers your power output, but you will be more aerodynamic.

Also check out ebay, you might be able to get both.

Since I am not planning on racing again this year, tri wise, I plan to use the aero bars on my bike all winter while on the trainer, to allow my body and muscles to get used to the new position. I my try the aero bars without the forward seat post for a while and see how that goes, if it is good, then I can use the $ to spend on a seat or other toys for the bike.