I love to cook and I love my induction range. But 30" is just fine. The only time I've ever wanted larger is when canning-- and then I'd be wanting another burner, not a wider stove.

Single 110v induction units are listed on Amazon for less than $200.

Thirty-inch is the sweet spot for all types of ranges. It's the market for which manufacturers compete most fiercely on features, performance, updates, and price. You'll find many more 30" ranges than you will 36". The Frigidaire GCRI3058AF, the least expensive 30" induction range (freestanding) is only $1100 and there are many reasonably-priced slide-in ranges.

I really like the added space of a 36" cooktop but wouldn't care for the huge oven which presumably would take longer to heat up. So for me wall ovens and a separate cooktop are ideal. That's what I had in my previous home but now have just a 30" induction range. I love it but at times it's difficult to fit two large pans on at the same time.

I think you will find the surface area easier to work with using a 36-inch induction cooktop (assuming wall oven(s)). You get 5 hobs. The larger base cabinet will better accommodate various sized pots and pans. My Frigidaire Gallery model only cost $1300 (plus extended warranty) about 5 years ago.

However, costs increase in the areas of ventilation and electrical connection. You need a 42-inch hood instead of a 36-inch hood, the blower needs to be a bit larger, the MUA system capacity needs to be a bit larger, and you will need (at least for my model) a 50A circuit (unit is rated at 43A).

Note for the future: There are no standard sizes for induction cooktop cutouts, or for the exact size of the surface overlapping the countertop. This may limit one to the same manufacturer if the unit has to be replaced, or lead to counter cutting and/or acquisition of a metal frame that adapts a smaller unit to a larger cutout.

She's looking for an induction range.

I have a 36" induction cooktop (Wolf), and it's great. I really wouldn't want to go back to a 30" cooktop. Which is why we are doing cooktop plus wall oven for our remodel. The total cost though is going to be the same or more than the lowest-cost 36" range. If we hadn't already bought the cooktop a few years ago, we would have just done a range.

That said, life is full of tradeoffs. I managed fine for years and years with 30" ranges. If you decide to go this way, spend what it takes to get the best burner layout for your cooking style.