Dynamic or not dynamic? that's the question.

For the OP, I'm going to take the contrary position for advice. Spend some time and effort on a bit of treatment. You've been doing this for 10 years. It is time to upgrade and invest.

It doesn't have to be perfect to make your recordings sound better in the room you are in. Also, the treatment doesn't have to be permanent or affixed to the walls. Gobos would be good solution and portable. I made lightweight frames for all my bass traps and wall mounted panels but as I was building them, I was struck by how light yet pretty sturdy they were. Most build gobos that are solid and heavy. These would easily free stand and stack.

I used a pancake compressor I picked up for less than $50, a cheap crown stapler and T50 stapler, a Makita portable table saw for less than $50 that I got on craigslist. A package of unfaced R30 insulation, some cheap burlap and dimensional lumber and you'd end up with a lot of sq footage of effective treatment for your space that you wouldn't even have to attach to your walls.

Robbert, for a paltry $20 US you could try a Behringer XM 8500 dynamic mic, they are really quite good and even if not even close to SM7b sound quality one should give you a very good idea whether a close up dynamic ,mic will solve your acoustic problems.

In anycase, having a spare, gash mic about the place is always useful.

Just ordered one the other day dude!
...but maybe how you are miking the voice up? Usually, going in closer, makes the room recede.
Before the thread spiraled down a rabbit hole, this point was made.

I wanted to second this suggestion. Even with room treatments, the vocalist still needs to be fairly close to the mic (the exception is in perfectly treated/high end studio situations where there's no negligible reflections above the noise floor).

How close are you? How soft/loud do your vocal passages get? If there's not too much variance in how loud/soft you're singing(*), then you should be able to get really close to maximize the input signal/gain without clipping. This puts your vocal's "loudness" well above any lower level noise and reverb from the room. I've personally done this trick in my previously poor recording environments, running the vocal input as hot as I could without hitting any limits, using moderate amount of gate to hush the inbetween quiet sections where there's no vocals, then adding my reverb / delay of choice, etc.

(*) If you're singing a lot of loud then soft passages, you might want to split them off into separate takes and/or tracks, just so you can adjust compression and other effects independently.
I n the Sound Reinforcement game there is the concept of "Critical Distance" which is iirc that point in a room where the reverberent level is equal to the direct level entering the microphone and is used to determine the 'gain before feedback' it is possible to get. The extreme case is the rock singer where the mic's mesh rarely leaves his lips.

WRT a very dynamic performance people should learn a good mic technique. Close for modest levels and back off a foot or more for the loud bits. Freddie Mercury is a perfect study for this.

Critical distance relates to intelligibility rather than feedback. It would be just as true for audio playback that doesn't involve microphones.