I haven't done the egg donation, but I have been on fertility drugs so often in the past that it is not funny.
There are side effects to the fertility drugs. Depending on if you do the pills or shots, that makes a big difference. The pills have less of a side effect, however, when you ovulate, your hormones go crazy and you will literally attack your DH for sex. As far as side effects go, I had tenderness in my lower abdomen by my overies and uterus. If you end up having a lot of egg sacks, there can be some mild pain because your ovaries do swell up a bit.
If you take the shot, then you have the injection site pain of course. I had to do shots for 5-7 days. They tell you to pick one place to do it so I chose the top of my thigh. It is a very small needle but if you move it while it is in you, you could bruise yourself. Side effects are similar to the pills only a bit stronger because the injection meds are stronger.
You are playing with your hormones when you do these fertility drugs. Just think of yourself how you feel about the time you would ovulate and multiply by 10. I went crazy with them, my DH loved it! Keep in mind that if you do this, you will have to abstain from sex or use very good protection in case of fertilization. Sometimes you can ovulate and you won't know you did until they do the ultrasound. You will be doing ultrasounds constantly to find if the sacs are mature enough for them to harvest the eggs.
The harvesting isn't difficult. The doctor will go in vaginally and use a small needle to harvest the eggs. You will most likely be put out with a mild sedative as they will have to dialate you and it can take a little while to get the eggs, depending on how many egg sacs you have on your ovaries. Afterwards, you should only have mild cramping and they will probably tell you to take it easy for 24-48 hours.
This whole process can be a strain on you due to the hormonal changes. Make sure you are prepared and that your husband is prepared on how to deal with you. You may be one of the lucky ones that it doesn't effect to much. Since you are so young, you have a good chance of fewer side effects. Unfortunately the older you get, the more they can effect you.
Having been an infertal woman for many years, I hope you are able to give hope to a woman who just can't seem to get pregnant with out help. Bless you for it. I know you need the money and that is probably your main reason, but think of the joy that you can possibly give to one or more women. There are a lot of us around who would love to have someone donate their eggs to them.
Having been one of the unfortunate women, I made a study of how things were done as I had looked into all the possibilities with every child I lost.
Good luck and I hope you make the right choice.