Baby needs a new pair of shoes

I have been on a search for shoes. I want to get Jacob a pair of leather shoes (like Robeez or Preschoolians) but I am such a cheapskate. I can't see spending up to $30 on a pair of shoes for a baby who will grow out of them in 3-6 months. I just want plain dark brown soft shoes. This way, they will match with everything and I won't feel like I need another pair to match other things. Although, I must say that of all the cute shoes I've seen, I really like these:

This is a Robeez shoe:

This is a Preschoolians:

This is also a Preschoolians: (of all the designs I've seen, these are absolutely adorable!)

What do you think? Have you seen any shoes like these? Have you seen others that are cute? Am I just being too cheap?

Here's the other problem: Jacob has small feet, but they are growing fast. Sizing him is kind of weird. According to Preschoolians, he would be a size 18, as his foot measures 4 inches (according to their accufit). That would be a size 3 (I think) in regular shoes. And they are only good for 3 months. In Robeez, I think he would still be in 0-6 month size, but getting close to 6-12 month. So which size would I get? All this stuff makes my head spin.

Any suggestions?