I'll wager a guess that the dealer ones have a real Timken, Fafner or NTN bearing in them, not a china POS.
I will chime in as we are one of the ones selling 3 kits (200, 400, 600, 3000, 4000, 6000 series machines) for around $50.., A couple points. One is who you are supporting and help keep around to support you and you equipment, Amazon or small business's? Two, quality difference on most things. Three, make sure you know what you are comparing, We sell the kits from $45, That includes USA Quality parts, Free shipping and we include 2 hard to find extra thick correct snap rings and 2 roll pins in each kit (200-400, 3000-4000 series) to complete the install as well as a making a full information and install video. Items are all inspected and packaged together. Also unlike Amazon and Ebay etc most times when you buy from a small web business you do not pay tax if out of state....I have one question whats the difference in the poor mans power steering you pay 50.00 from dealer, than the ones from Amazon for 6.00 or 7.00. Is quality that much better? Seems to me it's just 2 washers with needle bearing sandwich between, am I missing something?