I've bought a few things from Cabin Fever over the past year (mostly MTH warehouse auctions). Something to remember is auctions aren't by definition cheap. Sometimes you'll get lucky bidding on something that not many people are interested in, or nobody is dead-set on getting that particular item you've set your sights on.
When the auction closes, individual lots close five or six lots at a time (except for those that get bids within the last minute, then those re-set to two minutes until the clock runs out with no additional bids), and since CF auctions typically have around 600 lots, it usually takes a few hours for the entire process to conclude.
Owing to the way lots are closed out, if the lot you are bidding on is far down the line, you may encounter "competition" in the form of bidders who lost out on earlier items and may set their sights on (the thing you're currently high bidder on) as they look through the remaining open items looking for that "well I might as well get something today" items, driving up the price in the waning minutes of that particular auction. You can see evidence of this by looking at the winning bids on previous auctions (if you're logged in, you can see how many bids each item got). Doesn't happen all the time -- if its something with second or third-tier appeal they may not have the determination to keep feeding in escalating bids, but it's not unheard of for an item you had top bid on all day to rise out of your budget in the last ten minutes or so.
CF's buyer's premium is 15% added to whatever the total of your winning bids comes to. Shipping, packaging materials and the box itself is itemized and billed separately, and historically that bill arrives 5-6 days after you've paid for your winning bids (the last time I did on 8/31 the timeline from end-of-auction to box-on-doorstep was only four days, but I don't know if their process as a whole got a speed boost or I just got lucky).
If you've ever been dismayed by shipping charges on Ebay or any other online/brick-and-mortar dealer order, CF's won't offer you any comfort, and since nobody knows in advance how much stuff they're going to be packing for you, you won't know what the 'pack and ship' bill will be until after you're committed by winning an item or items. As with anything else in the shipping biz, size and weight determine a lot. A couple of postwar boxcars is certainly going to cost less than a pair of MTH autoracks (quite a few of them are in an upcoming auction in early October) will cost less than an articulated steamer.
---PCJ
