Are Facebook ads worth it for a tiny audience?

Hi folks, been doing a lot of reading up on Facebook adverts lately but still had a couple of questions. I've tried in vain to get them answered by Facebook's help centre so here goes -

1. My page has around 100 organic likes so far and I set up a campaign to target the friends of those liked the page. I have very specific targeting criteria and, after filling them in, the audience meter tells me I am too specific and my reach would be "less than 1000 people". I went ahead and ordered the campaign anyway. When editing the advert using the campaign manager, I'm given a more specific potential reach of 480 people

I'm perfectly fine targeting just 400 odd people as I know my advert will be highly relevant to them. But I wanted to know if I face any disadvantage due to the low audience. Does Facebook handicap/punish campaigns whose reach is so low? Will I be paying a lot more than usual for the likes? Will it be shown a lot less than usual? Secondly, am I right in setting a low budget for the campaign since the reach is so low? Or does that not matter since I will still be competing with other pages who share the same targeted interests?

2. The second question I had was why my reach was so low even if I removed all targeting conditions. If I were to just target the friends of those 100 people who liked my page, the audience meter still says my reach is "less than 1000 people". How is this possible? Assuming each person who liked my page has at least 100 friends (conservative estimate), shouldn't my reach be well over 10,000?

Thanks in advance.