I don't know how long the sale will last, but I plan on snagging at least the Orchestral Companion Woodwinds for $19.99. Might spring for the Brass as well.
I can vouch for the Harpsichord ($15.00) and Orchestral Companion Strings ($19.99). They sound great, as good as anything I've auditioned. The only gripes I have are that they advertise that Strings features swells available via the mod wheel and it does not, nor is there a manual with the product. But for $20 I let it slide.
Mixcraft 8.5 did have some trouble with Sonivox VSTi's for a few builds, but the issue was mysteriously fixed in build 412, so they should be good to go, and if you have any need for orchestral VSTi's, I think you can't beat them for the price.https://www.pluginboutique.com/manufacturers/156-SONiVOX