I'm invited to friend's wedding shower but can't go, do I have to give a gift?  

I think just a wedding gift would be polite enough. You did give her a gag gift and a you're attending the wedding after all, so I think you're alright. She should be understanding because you're putting a lot of money into dressing for the wedding and transportation there, she should be glad to have you there.

I think you have gone above and beyond since you have to pay for hotel and transportation to even attend the wedding. I'd say if you want to do something small then go for it otherwise, if you are not attending I don't think it's a big deal for you not to provide a gift for that event.

I think that you have done more than enough so I wouldn't give a gift unless the money is no problem for you

No, I don't think you have to. If you feel guilty about it, then find her a decent gift. But if it were me, I would save it for her wedding day in August. Just explain to her you can't make but will be attending the August ceremony. She should understand it. After all, you still need to save up for August. Money is a major during this recession period.

i don't know the etiquette for this but in a way if you already have a gift long before you learned that you can't come to the shower then send the gift. if you still want to give a gift even though you know you can't come then do so. but if you don't have a gift yet and you learned you can't come then it is your choice...