Two main questions here: 1, do the various buds(EX51, 71, 81 ect) utilise the same tips, or did Sony waste money by having each one require it's own tip? 2, where can I get replacement tips for my EX51(still have all the ones it came with and I don't anticipate any problems, but noone ever does)? And one last, minor, question, are there tips from other manufacturers that might fit on these buds? Mostly just curious as to how many options(if any) are avliable.