There is no guarantee that all inns will be reasonably priced. But most of them are conscientious! <br/>I recommend you to go to Tianyuankui Inn. The price of meals is definitely reasonable and the service is considerate. You can search on Dianping, Pingyao Ancient City is the first place. You can also save money by using Dianping.
The inns and houses are very distinctive, but the price is slightly higher in peak season, so it is a good choice if you are not sensitive to the cost. In fact, you can also live in a hotel outside the ancient city. Pingyao is not very big, and it is not too far to take a car or walk.