You might try googling "deflation bloggers" or something like that.
But I can tell you from experience that anyone who, like myself,
predicts deflation only gets crapped on by a lot of people, so there
aren't going to be too many people who are willing to admit that they
aren't in the inflation herd with everyone else.
There's no political support for deflation, which is why people get so
furious at the notion. People on the left want inflation so they can
pump up the stock market and spend more money on themselves. People
on the right want inflation so they can criticize the government's
monetary and fiscal policies. Real estate brokers want to sell
houses, stock brokers want to sell stocks, gold bugs want to sell
gold, commodities brokers want to sell commodities, and they all
depend on the (hyper)inflation party line to justify their existence,
and consider anyone not in that herd as a personal enemy challenging
their very existence.
Perhaps you might try to seek out a college where the economics
students have an online forum open to outsiders. College students are
usually young enough not to have become too committed to a single
ideology.
Another possibility would be the Fourth Turning forum, where there are
a lot of political discussions. I had several years of debates with
Mike Alexander (who posts under the handle Mikebert) before we had a
falling out. But he's done a lot of work on Kondratiev Cycles and may
be willing to debate you on inflation/deflation. At the very least,
if you start responding to his posts, then he'll certainly take you
on.
John