For me a pattern is now forming, and I can have a reasonable guess at what my orders will total.
In the UK a small part such as a single cuff or a sword is 10p, a hat is 15p, a shield is 20p, and larger or rarer items come slightly higher. A klicky figure is £1.65.
Assuming you add a hat & a couple of hand items (sword & shield) that comes to £2, which is the usual retail price for a special figure (unless you go to Hamley's), so you're not saving anything ordering normal figures this way. Any special that comes with more than that, e.g. the current greybearded cowboy, is extra good value.
OTOH, if you want a figure that only comes with, say, a full Knight's Castle, this is a good way to get one.