It is better to invest not in one cryptocurrency, but in several promising Altcoin. They are cheap and can bring good profits, unlike the unstable top crypto-currencies that have fallen and are in a flat.
Altcoin like ETH is of great value and importance in the current scenario. The current market value is $201 this 15th of October and allocating your $700 for this altcoin is worth going for because we might have altcoin more than $1000 in the next few months that might impart big value to your portfolio. Better sum up some more capital to your existing capital and invest it for long term. Eventually there can be big margins of profits.