I use the tea light mat molds and custom wick tabs I get from Candlewic. You can get the custom tabs with beeswax coating and they are very inexpensive. I then package the tea lights in the plastic cups, 12 in a craft box that I label on the outside and sell for $10.00/doz.
I don't like the looks of the tin cups. I think they look cheap and cheesy and, with the plastic cups, you can see the melted wax when you are burning the candle and it looks really nice. Of course, I color a lot of my beeswax candles so that makes a big difference also.
As far as not using the plastic cups in tea light holders, I have only once had a plastic cup melt so I would maybe warn potential customers about that but I don't think it's a big issue. Also, the plastic cups are reusable.
You will find that tea lights are probably the biggest sellers of all candles.