Has the OP settled on an option yet?
I think a valid option, even if just temporarily until a dedicated macro lens is found, is to use inverter rings. I bought two recently - 49mm and 52mm, for a total investment of about 10 dollars! There's no optical elements so it's not a problem if they are off-brand.
The beauty of it is that I can invert my 28mm lens and get extreme macro (about 1.7:1), and then I can use the 50mm or 55mm and get about 1:1 to 1:1.3 macro with very good sharpness (depending on how it's focused, it changes the magnification quite a bit). Or I can use my 135mm lens and get about 1:3 magnification.
Here's some cherry blossoms from my backyard...
Here's a bee on a dandellion, shot with the SMC-M 50mm f/1.7. Your 50mm f/1.4 would deliver similar results:
This is a center crop. Probably good enough for not being a 500 dollar dedicated macro lens...
These are weed flowers:
And the center crop:
But my favorite lens to take to a flower garden is the SMC-A 70-210mm f4. Not as sharp as a dedicated macro lens, only goes to 1:4 magnification - which is actually enough for most flowers - but to me it more than makes up for it with its wonderful colors. It also doubles as a fine portrait lens.