Voxengo also has a dozen or so freebies, at least one of which is a modeled guitar amp: https://www.voxengo.com/group/saturator-plugin-download/
Also VST4Free has a category for free modeled amps: http://www.vst4free.com/index.php?plug-ins=Guitar/Amp
And VST Planet has some: http://www.vstplanet.com/Effects/Saturation.htm
And another: http://www.wiredguitarist.com/2016/12/30/top-5-free-guitar-plugins/
DSK Music: (10 amps included) https://www.dskmusic.com/dsk-electrik-guitarz/
I got the above doing a couple of quick Google searches for things like: free guitar amp vst, and guitar amp model vst free. There were LOTS of other links listed, so you can likely find a whole bunch of them. I use the TH3 and Guitar Rig 5 Pro plugins, which are both paid, but the free version of Guitar Rig 5 Player is likely quite good, as the paid version is outstanding.
There is some overlap with the above links, and you will want to check versions when you DO find duplicates, so that you get the latest versions you can find for a given plugin. I would also encourage you to check out the other VST categories for these types of sites, as there are usually TONS of things like free effects and even synths, as well as presets for some popular synth plugins.
One more thing to check when looking for plugins to download - I HIGHLY recommend sticking to using 64-bit plugins, when using 64-bit hosting software, such as Cakewalk by Bandlab. 32-bit plugins in a 64-bit environment can be quite troublesome, and prone to crashing unpredictably. Yes, bridging software is potentially helpful, but not always, so I always try to avoid using any 32-bit plugins when possible.