Hi. Since you're on a budget, you could try going to thrift stores for the items you need. I've heard many stories of people getting their tweed jacket for Eleven from thrift. The shirt might be a little harder if you're trying to be exact. I know they did re-release the shirt, but I don't think it's available anymore. Besides, it was a bit pricey. I'd say just go with the closest button down shirt you can find. Skinny jeans should be easy to find. You can also check local shoe stores for the boots. Maybe check out DSW if you have one.
Also, a great place to find stuff is ebay. Especially, ebayUK when it comes to Doctor Who items. However, not all sellers will be willing to ship to the US, and if you find some that do, the shipping is hell. But, if you want certain, screen accurate items, it's certainly worth it. That's where most of my Rose wardrobe hailed from.
By the way, if you need more help with this, there's a whole Doctor Who subforum here. There are people there who would be glad to help you because I don't think I've done a very good job. Unfortuntely, I'm not an expert Eleven cosplayer.
Doctor Who forum: http://www.cosplay.com/forumdisplay.php?f=188