Calling all self-published authors! What size was your initial print run?

I'm at the point in self-publishing Granny Rainbow where I need to decide how many copies I ask the printer to run off initially.

Depending on the print method and quantity, the price per book varies significantly (as you might expect). At the moment, I have a price for 100, 250 and 500 units.

Initially, I looked at 100 units. But I got twitchy because it meant I had to bump the cover price up to make sure I had enough for the shopkeeper's cut. (I'm already working on a couple of contacts in the 'shop' department) There's something psychologically awful about breaking into a tenner and asking £6 for what is essentially a small book of seven short stories.

If I go for 500 units, I am going quite a bit over the budget I set myself for outlay but the cost per book is significantly reduced. A very attractive proposition, but I am struggling to get my head around exactly how much space 500 books of 100 pages each will take up; the WHOLE of my spare bedroom? Just a corner of the dining room? Every available surface throughout the house for years - until I sell them all or have a ginormous bonfire 'cos I can't stand the sight of them any longer?

Am I being completely unrealistic, expecting to sell 500 copies?! I know it'll depend on the type of book, it's audience and probably a million other factors too, but...

If you self-published printed material, how many did you plump for in that first print run?