we used the S&S old style capsule (newer model like Olive ) I used it for DD & DS & found it so handy (but heavy) I also heard the older style S&S are meant to be the "safest" capsule on the market so that also had something to do with it. I was actually going to get the unity for DS as it looks so comfy but was advised to stick to DD's old one as its meant to be safest.

Our meridian cost around $500... maybe even $550? Obviously some places have them cheaper than others.

Dont forget about the maxi rider which is also S&S & it fits up to 7yrs which your little man will now need (as far as I know) until he's 7yrs old. It takes from 6 months so if you're looking at having bubba in the capsule for 6 or so months maybe think about the maxi rider? They have it with AHR now aswell, just like in the meridian, which is what I got DD so DS could use her old meridian when he outgrew her old capsule.

Just thought I'd mention the maxi rider so you can do some further research

Hope it all works out with you MIL's purchase xx