My DD who is turning 5 soon has been into LPS's for about 2-3 years now. They are relatively cheap so I can't complain too much. She has a pretty big collection and still has not gotten bored with them, which is something rare when it comes to children and toys! lol Her other favorite things are My Little Pony and Barbie stuff but she plays with her LPS's the most!
In my time of shopping for these, I have found Target to be the best for two reasons. #1 they have exclusive LPS's found only at Target #2 They usually have a good variety including some of the "rare" ones. On vacation up north, I've found Meijers also to be a good place to shop for these. That is where I got the seahorse. Wal-Mart is good depending on which location you go to (I have two nearby, one has a very small selection and the other has a good selection with many "rare" animals.) I recently found the monkeys, chinchilla, and the new one with the pony in it.
As for the Hasbro website, I've ordered with them twice and here's what I can tell you. They are very slow with shipping. Their estimated shipping times are never correct. One of the orders I made recently said my item wouldn't ship for 4 weeks, but it shipped in 2. The other items in the order said they'd ship within a 3-4 days and it took a week. They also use the slowest shipping possible. It's been over a week and I'm still waiting for my Rarity unicorn MLP and mouse/rat LPS animals. I did, however, save 25% and get free shipping, but that's not that big of a deal since they often times go on B1G1 sales.
It would be nice to find a LPS swap. I've checked eBay and they want RIDICULOUS prices for stuff I can get at Wal-Mart for under $5. I'd love to get my hands on a large lot of them (unopened and pre-played with is fine!) for cheap. Or ones that she really wants but can't get because eBayers buying large amounts for resale. My daughter does not care about the "collecting" aspect, she just loves to play with them!