When I used to have my collection out, my mom would give me lectures on the amount of money I spend. But since I'm at uni, and she doesn't see it in such great quantities she's fine. However, when it comes to wearing actual makeup (as opposed to the monetary aspect) she whole-heartedly supports me. When she was my age, she and her sisters were the trendsetters that wore makeup, whereas everyone else in school was a "plain jane." So she gets it.
At first my sister was shocked at my collection (as I would show her every now and then.. and do her makeup). But whenever she got on my case for spending hundreds at MAC.. I'd tease her for spending hundreds of dollars on jeans. It equaled out. I eventually won her over by giving her Benefit and MAC for Christmas and her birthday. Now she loves the high end.. and I have one less lecture.
As for my friends, they're either supportive of neutral. The only time some of them mind is when I do makeovers on them (note.. makeovers apply to my guy friends as well). They think I'm a little bit crayzee for my obsession, but everyone has their quirks and this one's mine - and I'm proud of it. I'd like to think I've converted a good many of them too.