Yes, both SellerApp and AMZ.One offer a Free Trial.
SellerApp is designed for Large Enterprises, Medium Business and Small Business.
AMZ.One is designed for Large Enterprises, Medium Business and Small Business.
Pricing for SellerApp Starts at $39/Month when Billed Yearly whereas for AMZ.One Starts at $15/Month when Billed Yearly.
Some top alternatives to SellerApp includes Jungle Scout, CommerceIQ, Marketplace Manager, AMZScout, FOSHO AFF, AMZInsight, Helium 10, Omnyfy, Optiseller and OneMarket Insights.
Some top alternatives to AMZ.One includes Jungle Scout, RankActive, Outrankio, Sellics, K-meta Tool, Ranktracker, AMZ Alert, AMZInsight, AMZRank and Semrush E-Commerce Apps (Sellzone).