I own the Toon Maker 1 asset and also the Sam Base Model. I was wondering what other assets are out there that I could use that would compliment both of those items. I found Toon Grandpa, Stout Guy, Curvy Girl... But what else can you suggest would work and look good with that asset? Is Toon Grandpa and Sam Kid Base interchangeable with toon maker assets? I am not crazy about toon maker 2 style, so I am mostly looking to stick with Toon Maker 1.  I have iClone 5.51. And I also own Toon Town. So any interior toon assets would also be helpful. Any help would be very much appreciated. Thank you all!

Look at  3D Universe he created Sam, he has a list of all his available stuff ( Just for reference) and where you can get it. No Toon maker and Sam are different. He also has Toon Generations and a Sadie character. You can look at Daz as well he also has a professor which fit in with the toon aspect. Also Daz has a few other toon style characters. 

Toon Gramps isn't based on same mesh as Sam. I think a later version of Sam is Genesis based ( but not Gramps) 
Also a Rex character is a cool Toon style look 

also look to TokoMotion for CC toon stylistic characters...

Question do you know about Daz3D and using those assets in Iclone ( must have 3DExchange)?

Well I am aware of Daz. I just don't like using Daz. What I am more interested in really is props and assets that I can mix in with my toon maker characters. For example eye balls, clothing, hats, facial hair, head hear, shoes..etc.. that are not part of the main toon maker 1 pack. I found these:

https://www.reallusion.com/ContentStore/ccdproduct.html?contentid=AIC551CIENU012020141118003
https://www.reallusion.com/ContentStore/ccdproduct.html?contentid=AIC551CIENU012020141118005
https://www.reallusion.com/ContentStore/ccdproduct.html?contentid=AIC551CIENU012020141118007
https://www.reallusion.com/ContentStore/ccdproduct.html?contentid=AIC551CIENU012020141118006

But I am having a hard time finding any other props or assets that would work well with Toon Maker 1 besides these. Any recommendations specifically for Toon Maker 1?

NO sorry, I never got toon maker I had fallen away from Iclone when Toon Maker was big so never got it. Now although I am working with Toon style it's more the realistic toon style just to stay away from the Uncanny Valley. 

Hope you find what you are looking for.