To be honest I do not like roller trailers, I always use bunk type, now if you want a very cheap way to make it very easy to load and unload the boat buy a bunk trailer then buy a sheet of king starboard and cut strips to fit on your bunks, then drill and counter sink screws through the starboard into the bunks, what this does is acts as a very low friction surface and will help in shallow water where you have to normally back the rear wheels into the water for the boat to float high enough here you simply winch it on and its not like winching dead weight, take a look at some of my posts and you will find a jetski trailer I did this way, I have also done boat trailers this way and will do so for my speedster as well, just be carefull as while rollers spin these bunks also offer very little friction but are well worth it, expect to pay around $80 for the amount of starboard you will need, next a table saw and a router to make the edges pretty, then a drill and counter sink, and only use premium stainless screws. Once you use a trialer with these guides I doubt you will look back.
Also roller trailers are expensive and costly to maintain.
As always no matter what type you use always remember to have winch tight on front and both rear straps on and tight to hold the rear.