How long has the adwords been running?
If the conversion is good, and your in profit, its all good. But I kinda agree with your feelings, you should be converting more (Getting more sales for your hits). I always feel this way - no matter what, and it's healthy.
If people are clicking on an advert, being directed to your website, whats the bounce rate? (They just click off). If most are leaving straight away - then you MUST address the reasons for it.
Look at your website, ensure it's clear, attractive, and fully explains the key benefits and products you offer (This could even be done with a picture or two).
As discussed before, we have a home made website at the moment too. It isn't ideal, and we're looking to replace it. How does your site compare to what customers are expecting to see? If you did a search for a product, what would you want to see?
If you address this, then the people clicking off your website will be less, and conversion may improve. I feel this may be the issue.
Next, are your adwords keywords and ad content reflecting what your site is saying, and the services you offer?