I need a clear idea so I can start saving up and if I can actually do it :) Well if you dont know either but had a wedding, you can probably try and look around in your budget which you've spent around your wedding [depends if its a big one or not though] Thank you!
P.s Its a surprise silver anniversary for my parents, and my mothers birthday also. I have a brother who might be also willing to help me out. Hopefully :]
This is a difficult question. You need to give us more information. What country are you in, how many people do you want to invite, where do you want to have it etc.
Here is a list of possible things you can consider and maybe then phone around to find out the cost.
For my parents 25th wedding anniversary, we had their closest friends and their family members over. It was a fair size party of about 50 guests. Along with food and other things, it actually came to less then $1500. If you plan it right, it shouldn't cost you much.