Material first then shape (I tend to stay away from overly textured items) then vrooms. Cost is definitely a factor but I'd rather take the time to save up to own some good, quality toys that get the job done than a large quantity of mediocre quality toys that are just okay.
Shape comes first I'd say, only because that's usually how I shop/browse toys; look for a shape I'd like/enjoy and then check out the material. There definitely are materials I would never consider buying/using but my narrow down/shopping process usually follows the pattern of shape-material-cost.
Material. Right now I'm saving up to get the Raquel. It's the shape, measurements, everything as my fave dildo, but silicone. My fave dildo is made of unsafe material and I have to use condoms. I'm really looking forward to the day I can call Raquel mine.