All brides know that you have to have an invitation to invite guests to your wedding, it's one of those necessary evils. However, some people think they can get away with a certain 'budget' and quite honestly it isn't feasible... AT ALL.
When you are deciding your budget, regardless if you are going to make your own invitations, order online or have some super great company make them for you....ahhem, Lilac Suede, you need to be realistic in what you are wanting and the price you will pay for it. I know people think, "they are just going to throw them away, why waste the money". You don't want to look cheap or tacky, you want people to show up for your big day. If you're gonna be cheap, they'll notice; as your invitations set the mood for your day.
What you need to realize (and many fail to) is that you will pay at least $1.15 per invitation (and I'm being generous). There is no way on God's great Earth you can get away with paying any less, unless you're using copy paper and printing on your copier at work (hello tacky and cheap). Most places will charge you $1.15 for the invitation only, nothing else.
If you are inviting 50 people your budget is going to be less for invitations than if you invite 350 people, just like your food budget will be cheaper.
A good rule of thumb is to give yourself a $2.00 per invitation budget. You need to have an invitation and a response card, whether you're doing an online response or mailed, you need to have it. You may get away with paying less than $2/invite, so yay to you, more money in your pocket - but don't count on the fact that it will happen. It's always better to plan for more and be surprised when it is less.
Set a realistic budget for yourself or you'll be stressing over how in the world you'll ever get this done.