People on this board will tell you what you need to hear, not what you want to hear. You want to hear that you're a great biker and a great runner and you'll place well in your race and be competitive for the win. What you need to hear is that based on that one workout you described you're an okay biker and a pretty good runner.

Do you have potential? The answer is it depends. It depends on how hard that bike was for you, how much you've trained to get to this point, how much more you're willing to give to your training. At this point it also depends very heavily on your swim. Even in a sprint the swim will take 10-15 minutes for a good swimmer. That's not something you can fake your way through and then crush it on the bike and run.

Get in the water as much as possible this month. Mix it up. Swim as many 50s and 100s close to all out as you can. Swim slow for as long as you can (shoot for 1000-2000yds continuous). Watch as many youtube videos on technique as you can find. Here is a great resource for workouts: http://mastersswimworkoutsbysaramclarty.blogspot.com/. At this point do whatever you can.

As far as wheels go, buy whatever you can afford. A cheaper wheelset like Mavic Cosmic Carbone SL's or Planet X or FLO with a disc cover will get you >95% of the way there. Some people argue it'll get you >99% of the way there.

I don't know what successful biking means to you but in a Sprint and Olympic distance race (which I'm assuming is what you're training for) if you want to be competitive on a local, age group scale you'll need to be averaging upwards of 23.5mph and be able to run under 19 minutes for a 5k or 39 minutes for a 10k. That is showing potential on a local scene. If you want to talk about potential on a national age group or back of the pack pro scene I can give you some numbers to shoot for as well.