I bought my shoes and pedals at the same time. I just bought the cheapest ones on the shelf that fit the cheapest clipless pedals, and I'm plenty happy with it.
I'm sure there are advantages to the higher-dollar items, but if you don't intend on racing, I really don't think it's worth it to save 8 ounces of weight by getting the "superior" items.
I spent around $120 for Shoes, cleats, and pedals. Just the other day I had to take my dad's bike out for a spin, he has toe-clips. My feet fit in those just fine for the 12mile trip.
I should note, however, I don't wear the traditional cycling shoes. I wear the mountain bike shoes that have the recessed cleat. I find it is a lot easier to walk in these than in standard shoes. I'm sure standard shoes there are plenty of riding advantages, though.
If you just want clipless pedals for the basic advantages, don't bother getting the high-dollar ones. If you want them for their racing advantages, you're better off with the pricey ones.