I don't fit your request for an expert, but as I was just starting to research recessed lights for myself recently, I found something called the Ecobulb Plus by Feit Electric. They have less mercury than normal CFLs, and even tout having less lead in the bulb reflector and screw area.

If you scroll down to ECObulb Plus Indoor Reflectors and Hard reflector sections on the link below, you might find something that will work with a 4".

Seems like these bulbs aren't available everywhere, but I saw them at a local hardware store. The site also says you can get them at some Lowes, Bed Bath Beyond, Costco, Walgreens. I would definitely talk to the person at the store to make sure they would work with your can.

In regards to cost, I was looking at some R30 for a 6" can. It was $20 for a pack of 4, if I remember correctly.

Here is a link that might be useful: http://www.ecobulbplus.com/ecobulb_plus/ecobulbplus.html

Thanks for the tip, I will check it out. Does anyone have a good source for LED bulbs I would like to check those out as well. In looking online prices are all over the place

This is the best price I've seen, for a LED w/ good output. However, it is for 6" cans.
Lithonia Reality LED Recessed Can Kit

Thanks, that's a great price. Will try to talk the wife into a larger can

You may want to look at the CREE CR6 series.
polar-ray - 64.99
Home Depot ~49.97

Definitely not an expert - but after much research, we've decided on the Cree CR6 in a 6" can that we bought for $4.75 - so a grand total of around $54/light (got the Crees at HD for $49.97).

Analysisparlysis - your total cost of $54/ light is impressive. Where where you able to find the cans so cheap?