Any mixing wagon or grinder/mixer needs scales.  I've done without, and although scales seem expensive, they will pay for themselves over and over. In time and mixing accuracy, especially w/ dairy.  Unless you got kids who need to be kept busy, I'd really look at a Knight reel mixer w/ scales, can be had for around $8k in the midewest and surely less than $1k to ship it.  Will give you a lot of flexibility for feeding forages, grains and byproducts of all different moisture levels and easy as backing it under an auger or using a loader to dump right into the top.  A grinder mixer is limited to dry feeds with a flowability required for augers.  Just think with you starting out where you are at, an investment in a mixer wagon will give you a lot more ration flexibility as well as be a huge labor saver as you can feed into bunks, take it out into the pasture and dump it into a windrow along a hotwire, or dump it on a pile and feed it with buckets or a loader.