For my money, this is the creepiest item in my collection, and the only item I've ever considered getting rid of. I bought it on ebay a couple of years ago from a seller in Canada, so I assume it's Canadian in origin. The ebay description was extremely sparse. "Youth Tim Wallach Jersey," and the photos weren't great. I couldn't seem to take any decent photos of it either, you may notice the three different backdrops showing up in the pictures I've provided, the weird thing just doesn't want to be photographed.
I believe it's home made. It's either an incredible home made uniform, or the worst produced commercial kids uniform ever. The letters in "expos" on the front are the best argument for it being homemade. But the "lg" on the back pocket of the pants looks like some sort of brand logo. But that could just be a brand of generic uniforms that someone used to iron letters onto.
The material is very similar to the Little League uniforms kids wore in the 1980's. However I don't remember ever playing a team with the names of MLB players on the back. My final working theory is that this was some kids Halloween Costume. Which is a little strange. Why save a costume someone clearly put a ton of work into for 25 years just to dump it on ebay for $15? And if some small Canadian kid liked Tim Wallach enough to go as Wallach for Halloween, why wouldn't they want to keep it? I never went as Wallach as Halloween, but I did have Superman birthday cake mold that was used and frosted to look like Tim Wallach when I was about nine.
In any event, I find this item to be a little off-putting. Less an item of Tim Wallach memorabilia, and more an item of memorabilia from some anonymous Canadian's childhood.