The reviews for Whispering Surf are not good at all and if you go google and type: google maps
You will be able to zoom right in and see the sites and some with RV's on them and it's free to use. It sure doesn't look to me like Whispering is anywhere near a $60/night CG.
Mears State Park in Pentwater if they have any availability. Timberlake Resort CG south of Pentwater is on the east side of Ridge Rd that runs along the lakeshore. Haven't been there in many years but they always had a LM beach right across Ridge Rd, about a 2 block walk from the CG. Several at Silver Lake but it's a busy place. North of Whispering and just south of Ludington, there's Mason County CG on W. Chauvez about 1/4 mile west of US-31, right next to the north end of the big pumped water storage basin on top of the dunes. Several private CG's at Ludington but you'd be insanely lucky to get a site at Ludington state park as is always book solid like Grand Haven and Holland State Parks are.
CG along Lake Michigan are extremely popular and fill up or reserved all summer long. There are cancellations so don't give up. Much of the problem is some RV'ers are very self centered and rude and will reserve at several places or reserve under more than one name for various weeks and then cancel at the last allowed time the sites they aren't going to use and the sites then become available again. Some people are just selfish ME, ME, ME and the heck with everyone else.