You are a bit behind the times buenochico. I'm going to a very fancy wedding in may - invitations were designed on line by the bride and groom with individual printed names and then printed and delivered to bride to be addressed by hand. Certainly NOT £5 each. Oh and I have never come across a wedding number one where the parents were not invited considering they are often expected to contribute!
If I received a wedding invitation by email I would not be offended, personally speaking, but honoured.
Then again society seems to think you have to spend a fortune on wedding day. Doesn't seem to have helped the divorce rate.
depends on how many people going and how old they are, I expect. All 20-year-olds is probably fine. Older people or more traditionally-minded ones might like a printed invitation as a souvenir. They don't have to be expensive unless you've got a four-figure guest list.
If you want to keep it traditional, you should send invitations through the post. If you're not bothered about that, you can do what you like. Your wedding, your rules.
well, it would be nicer if you sent them by post, but it's not a crime. if it's someone living abroad and you know it will take a couple of weeks for the letter to be delivered, then why not?