Sell and collect donations through PayPal for non-profit

I am designing a website for a non-profit, they want to sell memorabilia & collect donations through an extensive donation form, I can’t find a plugin that could do both and end up in the same cart. Can anybody suggest me something. I can code the form in html, don’t know how it will add up the Several steps of donation in the end and checkout through PayPal, I ll search on that. I just want to have one check out the shop and donations. Help!