Went through same thing last summer... My little one is left handed as well. I actually found one on ebay for about $20 bucks, and it appears they have several on there right now. Just do a search on "left glove 10". Just make sure they note it's a glove for a "left hand thrower". My husband said he went to Dick's Sporting Goods the week after I got it and they had a bunch in the store, maybe it just depends on when they get their stock in. I'd call and ask them, couldn't hurt. I'm left handed as well, but I throw with my right, I'm all screwed up
I have one you can have. We bought it by accident and could not figure out why my son looked so awkard when he played. We finally realized what the problem was but it was too late to return the glove. PM me and we can make arrangements to get it to you.
