If you're serious about wearing a 60 inch wig, be warned that it will most likely tangle. So use a detangling solution before you wear it any where. I hear Epic Cosplay's wigs are less tangle-prone, here's
their 60 inch wig. Here's their
50 inch wig.
The only way to keep this project under $100 is to combine two shorter, less expensive wigs. Or one wig and one pack of wefts.
Arda's long wefts are 36 inches, and cost $15 a pack. The final option is to find less expensive cosplay wigs on ebay, and combine the two that you need.
If you need tutorial, look up the process of cutting a wig (if using two) or adding wefts to a wig.
Here's a tutorial for adding wefts.