Well there are many billing and automated webhosting scripts/panels that are out there. Some are good, some are bad, and the cheap ones really do suck.

What are some control panels that are actually worth it for the price?

I have heard of
ihost
ipanel
phphostbot
clientexec
modernbill
whmautopilot

I am thinking of buying clientexec, what other options do I have, i need something simple that doesn't error out. I currently have iHost but 60% of the time it fails to create an account and I have to email the paypal owner to give me the information to setup.

Well there are many billing and automated webhosting scripts/panels that are out there. Some are good, some are bad, and the cheap ones really do suck.

Be careful what you say, because you're just opening yourself up for problems there.
When you pay $20 or $30 for a billing client, of course, you're going to get crap software. This isn't rocket science, at all.

One that you haven't put on your list is whmcs (www.whmcs.com). For the price, you really can't find a better client. They top every client in your list that I've tried (whmap, modernbill, clientexec) and a few that aren't there(awbs, ubersmith, whoiscart), and for around $15/month (or $150 full purchase IIRC), they're 100% worth the money. Support/Billing/Affiliates, it's all there, and the support FOR whmcs is incredible.

Yeah WHMCS seems pretty good. Though the pricing is making me consider ClientExec. I'll wait a month and see how my overall revenue is doing.

Clientexec is better than others which in your list.

Yeah WHMCS seems pretty good. Though the pricing is making me consider ClientExec. I'll wait a month and see how my overall revenue is doing.
If price is a factor, then lease it until you can afford to buy it all out.
CE may have grown over the past couple of years, but it's not as good as WHMCS is/can be.