For those considering FBA now that the amazon holiday selling rules are in place, I would advise against it.
As Bold-Arrow said, FBA has its pro's and con's. I'll try to run through a short list of them, but it's worth searching out more details on this forum, the brickset forum, and elsewhere before you take the leap. Search for "FBA horror stories" for a sampling of all that can go wrong.
pros: higher selling price, amazon handles the packing/shipping and all the customer service
cons: storage fees, amazon handles the packing/shipping and all the customer service
The seller needs to pay shipping to get the items to an amazon warehouse, so there is still that. There are horror stories of shipments being lost or misdirected though.
_IF_ the sellers stock is co-mingled with others, there is a risk of a product being shipped to your customer that is in worse shape (or even the wrong item) than the one you sent to amazon. It costs more to keep your product separate from the co-mingled stock.
_IF_ the buyer has a complaint, the seller has very little recourse to resolve it. AMZ handles the customer service, and decides how much credit to give for a claim.
Bottom line is that if you are quick-flipping and/or have high volume, FBA is probably OK---you can ride out the hiccups.
If the items you are selling are very valuable, and/or rare, I would avoid it.
I've looked into FBA many times, but have decided against it (for now, that may change if I run out of space in my closet). For me, the risks of something going wrong are just too high. I'm a hobby seller, and average 1-2 sales a week when I feel like selling stuff. My volume is so low, that if a sale went bad, it could wipe out my whole profit for the month. Through FBA, you're bringing in a third party, and so in my opinion the chances of something going wrong increase dramatically.
If my sales were much higher in volume, I would probably see more benefit than cost to the FBA program.
Similarly, if your volume is so low that you didn't make the '25 sales in 8 weeks' threshold, FBA may be riskier than it is worth.
Just my 2-cents.