I'm not going to suggest a bentwood case - but that is an option if you want. Other than looks, I don't see any advantage to go with that over either of these two - it's going to cost more also - your best bet to get one is buy it with a crappy looking 66 inside. I can't say for sure that the 201 will fit in a bentwood case. There are two sizes of these too.
This is what my DH's 201 "portable" came in. It's about 15x21
Do Not confuse this with it's much more common smaller sister - that fits the 301. the smaller one measures about 13 x 18. The 201 will not fit in the smaller case.
This is the base that the 201 came in.
The nice thing about that style case, you can carry it by the handle, the bad part is it's a pain to get the heavy machine in and out of it.
If it isn't already this way, I'd suggest wiring your 201 to take the two lead plug (like this one) if the foot pedal is hardwired, it will be alot easier for you if you unwire the pedal and get a two end lead and wire the foot pedal to that (you can buy it with or without the pedal attached).
This is an older style case - and there are two sizes, the smaller fits the 99/128 (this is pre 301).
Here is what the base looks like.
With this style - you probably don't ever want to pick it up by the handle. Use it only to lift the cover off the machine.
Though this style is harder to carry, it's easier to get the cover off the machine.
My advice - if you really want a vintage, full size Singer to carry around - get a 301 and put the 201 back in the cabinet. Unless you are into weight lifting and have a really strong back.