There's a couple of other factors with BIN vs Auctions aside from the cost, IMO. With auctions, you can have a set time once or twice a week, for example, that your items will end, which puts you more in control of how much packing and posting you do as well as when.

With a store, sales are likely to be more sporadic, taking up bits of time here and there rather than all in one go. In that way, maintaining a store can sometimes be a little more time consuming even with less sales.

Auctions can be a little more conducive to faster turnover, as well, so in deciding which is the better way to go I'd probably look at whether I'd prefer to clear out the items quickly, at prices decided upon by the market, or spead it out over time at pre-determined prices.