OK...maye it's time to narrow things down and just cross of things from the list, while adding a few things
100 2.8 macro usm
100L 2.8 (cost is too high, overlapping focal length) 180L 3.5 (High cost, overlaps with 70-200, unless I can see some portrait examples taken that beat out the 70-200, the cost outweighs the need)
close-up lens filters
If L quality glass is crossed off the list...how do tubes or filters stack up against the cheaper lenses? It's process of elimination time!
PS - mind you, if I take one of the cheaper options (tubes or filters) and end up digging macro work and want to take it a step further, it's not like I can't step into one of the higher quality lenses --- lol... kind of like doing a wine tasting, if I like I can always buy a bottle...