On the one hand, we all want to spend as little as possible. On the other, we all pull our hair when we ought to be getting results we want. In normal picture taking, this isn't an issue ... but you you're approaching a threshold.
What do you want to accomplish with a shorter lens ?
( OK.... I mean a whole lot with this question: I was a trained photomacroscopist in another life )
Depending on your intentions, the 28 Componon will do fine, or be a miserable failure.
There is a good availability of REAL macro lenses ( Nikkor, Olympus, Canon, Leitz, Zeiss... older B&L ) that are generally cheap ( so, maybe not the Zeiss ) and wonderful.
When we get down to 28, focus accuracy is SO important we're beginning to exceeed the performance of a 35mm camera and bellows ... even the Nikon. But for some work you can use it just fine. So.... as my mother-in-law once asked me, "What are your Intentions ?".