Macro lens

I have the sigma 150 and it's really sharp but not cheap

The Tamron 90 is cheap and really good

The nikon 60 and 105 are both good

For flowers I doubt you need 1:1 (otherwise you will just get isolated stamen shots and miss the rest of the flower so you may find that the following are nmore suitable than a dedicated macro that maybe too close for what you need

Dioptre - screw in close focus lens - like a filter on your normal lens;  gives good close ups, not as perfectly sarp as a dedicated macro but at 1/5 of the cost of a macro a good way to get closer

And / or extension tubes - by fitting these between the lens and the camera you will gget closer focus without loss of quality but whilst they are on the lens will not go to infinity

Again much cheaper than something that will possibly take you much closer than you require

3rd party lens with 'macro' function - will get you to 1:3 normally, not a true marco but as close as you may wish to be

My favourite close focus is a manual focus 28mm ais - focuses to 20cm from the sensor place and gives a great and different perspective, I use it for fungi, incredibly sharp