Does the iud contraception have an effect of weight gaining wen taken? and roughly how much does it cost?

Long-term insertion: The IUD is a device, you do not ingest it. I does not mess w/ hormones so there should be no weight impact. Cost is hard to say from culture to culture - but in the USA, insertion is the expensive part. A provider must do it. You can find this info locally. It does nothing to protect against STDs - so that can still be a big concern for some.