That is a nice return if you chose to sell. And it wouldn't be a bad time to cash in either because the prices are low, so you'd be able to get a stack of shiny from selling one of those. Those Pandas are also 1 ounce coins. A lot of the ones that I've seen have been 30 grams. Good finds.
I haven't been collecting long enough to have had mine go up in value. It's been less than a year and the prices have been dropping, so I think most of mine are under water right now. That's ok though because I'm planning on holding on them for a while.
I should have said I bought all 4 for £100 ($125US), so hopefully I should make a return.
That's a pretty good deal! In 3 years you can sell one to more than cover the cost of buying all four. I'd say that's a good investment.