1) Who is the developer of this project please. Is it gjhiggins?
2) Why the coin price is very low did the original dev left?
1) It's a FOSS project, I'm merely one of a number of contributors.
2) Yes the original dev left (it's at the end of the OP but it *is* In the OP):
https://bitcointalk.org/index.php?topic=613213.0 (The original Slimcoin developer has not posted in this forum since the end of 2014, and he has stated that for the moment he is too busy to continue maintaining the coin. Some of the links in the release announcement are outdated and the formerly official website is offline now. So some members of the community have decided to restart the thread.)
(how that relates to your perception of very low I couldn't say)
Cheers
Graham