Don't let your eyes pop out.
Things like Acquisition can look fine, but that's not always the best solution - especially if you're selling to the world of business. There it's more important to make the program easily identifiable - something IBM called the 'Recognition Principle': programs are supposed to look similar. That's the whole point! If you're marketing a consumer app, then going through all that trouble like Acquisition might be considered necessary. But if you're doing a custom job for a client, then definitely do not do that. People who purchase your custom software want to use it, not look at it, and they want to start using it ASAP.
And don't forget: it takes a lot of work to create an add-on. It takes a lot of testing and debugging. And be so sure that just when you think your fancy control is ready for prime time, someone will discover yet another flaw.
That is why there are UI elements provided for you: so everything looks the same (Recognition Principle) and because creating flaw free elements is really hard work - a lot harder than you may imagine.