I don't know what you wish to use them for, nor the exact method of modeling used by Form Fonts, but you could try using the Artisan plugin to sculpt some low rez models for Sketch Up, or if you need really good quality posable models you could use Poser or DAZ3D...
DAZ's models are fairly affordable and DAZ Studio 4.6 is still free, so if you don't want to spend a lot on the program its not bad.
You can export the models you make in SketchUp into OBJ format using Pros native OBJ export or TIG's Free Object Exporter... once in OBJ format you can import them to Poser or DAZ studio.
One thing to note, DAZ base figures are nude, so you need to buy clothes for them (or not)... which is basically how they make up the cost of the free program... Poser on the other hand does come with a whole lot of free content as well as several clothed figures.
If you go for Poser, try finding an older version like Poser 8 or 9 on Amazon, you will save a lot.
Edited to add... sorry I just notice you said "for SU"... Well, Poser models are pretty detailed and make huge SU files in general...
I sometimes pose and export DAZ people into SU using an older version of DAZ which had a Level Of Detail option for certain figures... I drop the LOD pretty low, since I need the figure only for scale reference... I don't know if LOD export is possible in Poser, or how it now works in DAZ Studio (I think you now need a $$ plugin called "Decimator").
I hope this was of some use.