I've noticed a few words like these:
恥ずかしがり屋{や}
寂しがり屋
怖がり屋
I've only noticed this with a few adjectives, like the ones above, and with verbs with たい:
目立ちたがり屋
I suppose this ending is just a combination of がる and 屋. I thought that perhaps がり屋 might be considered a special combination, but I couldn't find it in any dictionaries. I did find this definition for 屋 in 明鏡国語辞典, which I think is the relevant one:
それを専門とする人や、そのような性質の人である意を表す。
We already have a question asking whether 〜がる is limited to specific adjectives. So I guess the question I want to ask is this: can I use がり屋 for any word where I can use がる? Or is it strange outside of those few words where it seems to be commonly used, like 恥ずかしがり屋?