That's not a bad price for a T. blondi sling (at that size it's probably a new emerged/free feeding 2nd instar). Blondis don't produce a lot of young and they're high demand on account of their size. If you're able to pick it up at a store for that price, go for it. You can find it online for $30-$40, but then you've got to figure in shipping.
We got one from www.krazy8sinvertebrates.com for $50 bucks that is pushin 2.5 inches. I order most of my T's through this site. Chris gives you quality animals, healthy, nice size on them too. If you givem a try tell him Uncle Whitey said hey. lol
It's not really a bad price. Try and find some people in your area that are also looking for T's and split the shipping. Or you could always buy more T's so your getting more for your $20 shipping charge.