I live in Wheeling and just started using the Claude Thomas salon. The owner, Claudia Tapp does the hair replacement part of her business, and will cut in your system herself. She's awesome and did a really good job the two times I've been there. Cost: $65 to cut in longer hair. Offers late evening hours.
The info on the salon is below:

Claude Thomas Hair Design & Spa
Claudia Tapp
377 W. Northwest Highway
Palatine, IL 60067
Phone: (847) 705-5999
Email: <!-- e --><a href="mailto:[email protected]">[email protected]</a><!-- e -->
Web site: <!-- m --><a class="postlink" href="http://www.claudethomassalon.com">http://www.claudethomassalon.com</a><!-- m -->

You can also try Bloombrook International. They are located at 17w705 Butterfield Rd Oakbrook Terrace - (630) 705-0011. I heard they do really good custom cut-ins. Cost: $100.

I also found White Cliffs Hair Replacement Studio at 17W662 Butterfield Rd. Oakbrook Terrace, IL 60181 - (877) 713-4247. Cost: $95
Website: <!-- m --><a class="postlink" href="http://www.whitecliffsgroup.com">http://www.whitecliffsgroup.com</a><!-- m -->.