Hi, I've had a quick look at your site, and all of what's mentioned here applies to a degree. I hope you don't mind me giving you some pointers from my old consultant days (i'm really not a great one to talk as I'm currently struggling to get suppliers to supply an ecommerce only venture - so I'd welcome your thoughts on this in return).
Your site looks great, and is well laid out. However, whilst it's true that you shouldn't discount all the margin out of the products, from experience I believe customers use the net looking for "bargains". Just look at Amazon etc, there's always a prior price on there or vs RRP. Your site doesn't offer a sense of getting a bargain. I believe you could increase your conversion rate by making the site more "selly" - try some time limited offers, flagged clearly on the front page. this works wonders. In terms of your arts and crafts products, I believe they would benefit from photos showing the products being used - add some fun to it.
Hope that helps at all - the site looks great.