How can I get involved now if I have missed the buy in etc.?

also you can buy some in Polo,
it is not late.

Polo is the most active exchange but as of yesterday we have now been added to ALTS.TRADE. I don't really know them well and I believe they are pretty new on the scene. So always be careful and pay attention.

Below is the list of all current exchanges that support SJCX.

Counterwallet DEX: https://counterwallet.io/#
PoloniEx: https://poloniex.com/exchange/btc_sjcx
Melotic: https://www.melotic.com/markets/sjcx-btc
MasterXchange: https://masterxchange.com/market.php?currency=xcpsjcx
ALTS.TRADE: https://alts.trade/trade/SJCX/BTC