My fiance and I are getting married next year and we are paying for our own wedding without outside help. We formulated a solid list of people we want to invite to our wedding and we decided to have an engagement party. We started to invite our wedding guest list guests and now they are all RSVP'ing with their significant others/husbands/wives/friends etc. We are really concerned that this sets the precedence for the wedding, and we can't afford everyone "plus one." Yes, we now have heard "Well, didn't you know when you invite someone who's dating/married/engaged etc, they automatically get a plus one?" but no one told us that

Where do we go from here? We've heard the extremes of "put a no guest policy on your invites" to "don't worry about it, people won't show and it will even out." The first extreme sounds a little rude and the other extreme means people we don't know at all will be at our wedding, at $125 a head.
Help!
Thanks!