The Question is: Should I pay for a sign design? The answer is, Yes, and here's why.
If you get a free design, the sign company owns the design. You are limited to that sign shop for that design. Will they offer a sign and a design that's best for you or for them? Do they use quality materials and give a fair price? 
I am a designer and consultant. After 30+ years in the sign business, I know signs, materials, how to make and install them.
From simple banner designs to complex signs that require engineering seals. 
I understand Zoning issues that determine type, size, colors and quantity of signs allowed. I can testify as an expert at town meetings, get or help you get a zoning and building permit. If you need and installer and or an electrician I can help you.
You will get a quote of what your sign should actually cost, so you can shop get the best price. Or if you like you can buy most signs that I design at a discount price.
You pay a low hourly rate or by the project. I have had thousands of customers that were happy with the pricing and service and I bet you will be to. 
Please call to discuss your sign project. 
Thank you 
Brad O'Connor