I just finished putting together a tidy little excel spreadsheet to track my cyptrocurrency purchases and gains.
I thought I might as well share the file here so you don't have to go through the trouble. You can download the file here: https://drive.google.com/open?id=0B3EiA_hldf1BaldMX1hZS0tEUWc
This has a live link to coinmarketcap.com and works with all listed cyptocurrencies (1000+). Just fill in the name of the cypto and the amount you have. It also links to live FIAT exchange rates so it should work in any country.
To add more options click and drag across a new column in the portfolio section and type in the name at the top.
On the 'purchase history' tab you can keep track of each of your buys and sells, and the exchange at the time. The spreadsheet can then use this to calculate your gains/losses. Its good to keep these records for tax reasons.
Big thanks to @aacoimbra and his post here. I copied a lot of his method. If you found this helpful or want to know more about how to set this up yourself please go upvote his post.
If you have any troubles let me know. I did this on excel 2016, if your using an older version you might need a XML source map plugin.