Agreed regarding best service, (and not the cheapest). To fairly compare costs between brokerages, though, average trade size and monthly trade volume must be considered. The set and quality of trading tools and data provided is also a big part of value. For me, TNMB is a good fit.
Whether low, fair, or high, that's an individual call, but here's the Terra Nova-MB commission structure:
Tier 1: $14.95 (1 - 249 trades per month)
Tier 2: $12.95 (250 - 499 trades per month)
Tier 3: $ 9.95 (500 + trades per month)
ECN Fees:
Instinet (INCA) $ 0.01 / share
Attain (ATTN) no charge
Archipelago (ARCA) $ 0.003 / share
Brass Utility (BRUT) no charge
Bloomberg (BTRD) $ 0.008 / share
Island (ISLDA) - adding liquidity no charge
Island (ISLDR) - removing liquidity $ 0.0025 / share
NexTrade (NTRD) no charge
Speer Leads Kellogg (REDI) $ 0.006 / share
NYSE (ISI) $ 0.0055 / share
AMEX (ISI) $ 0.0055 / share
Monthly software and data is no charge after 50 trades.
Regarding other RealTick brokers that have trailing stops permissioned, I can't say.