ABS is cheap and shrinkage control is easy for your tooling guys. The recommendations seem to be on the spendy end of the scale.
As for designing the part, why not just hire a guy and bill back at +20%? Seems you would more than enough time to justify the cost.
And are you in China? Plenty of English speaking RP houses who can print a good part. I have used star prototype. Nice folks. Otherwise, if you are in NA, why would you go through the hassle of getting a small part in China while you are still evaluating the design? Get a guy down the street who will print the part and have it available the morning after you sent the file. A small snap would run me about $20 in the accura clear. And I use than material whether the clarity is needed or not. Like I wrote, flexes well, detail is outstanding and cheap.