I would say put all the 1800 dollar into SONM, hold your tokens for atleast a year and enjoy the profit. SONM is doing a great job, they are not at a conference in Barcelona to promote their company and show what they have done so far.
Thanks for your answer
Where is better to buy it? In btc or eth?
There is not really a difference in the btc and eth price if you convert it to fiat. I recommend you to use binance.com for exchanging bitcoin to SONM. Hold this coin fir at least a year. It will give you alot of profit on the long run, don't daytrade this coin.