I am not a php guru, or a coding expert. My website has been developed by lots of hard work, lots of time, lots of trial and error and an awfull lot of help from the oscommerce community. I knew nothing about oscommerce when starting, and do not know a great deal more now. What i do know is how to slightly modify my store, and how to add contributions.
The store does what it should, and that is to sell products that i design and make. It may not be the prettiest store out there, but it works, it is simple and customers use it. What more can you ask.
In the forums i try and answer questions and give help and advice, where i think i can help.
Use oscommerce, it does what it says it will.