First of all, congrats on getting Espadia!
Secondly, I know it's not specified in the Show & Tell Rules, but... I think it's not a good idea to start a thread in the Show & Tell section if you don't have any actual photos to share. Just saying.
Thirdly, in response to your question as to what other Shinki are worth nabbing that aren't super-expensive? Unfortunately what few Shinki out there who aren't super-expensive are the EX sets like Waffebunny and Waffedolphin who don't come with bodies and the not-so-popular ones like Xiphos and Benio. And it's really hard for me to answer which Shinki that I think are worth nabbing, because the ones I think are worth nabbing may not be worth nabbing to you. You probably don't want any of the Light Armor Shinki -- Partio, Pomock, Harmony Grace and Bright Feather to name some -- as their armor only has one configuration... and you said you're looking for the Shinki that excel in armor building and modularity, so... there's at least four Shinki I recommend getting that don't fit what you're looking for (unless you have plans to customize your Shinki by giving them armor that doesn't come standard on them like what ZeroEdge has done with his). So... my best advice is to just look at every single Shinki that has been released, make yourself a list of all the pros and cons to each Shinki, and then determine the ones that you absolutely must have... and, if necessary, start saving up money for the ones you want that happen to be really expensive.