i just posted the same question, and bought the Legrande undercabinet strip on Amazon - you can find it elsewhere too

https://www.amazon.com/dp/B0848NBNGC?psc=1&ref=ppx_yo2ov_dt_b_product_details 

I don't think a combination of outlets and plugs would be very practical. Outlets are less obtrusive next to the wall; under cabinet lighting should be placed at the front of the cabinet.

Thank you Sally! Legrande also pointed me towards lightbrothers who have a decent amount of stock. My concern was why it was discontinued in the first place but apparently it was simply supply and demand and not any quality issues.

Also search ebay for "legrand adorne cabinet". Some pieces (e.g., track) were cheaper than at https://www.lightbrothers.net. Total price adds up quickly as the components are expensive.

@jeffery,
Curious what did you ens up going with?
We are facing the exact same issue.
Thanks

We ended up using the Legrande system that we originally specified. Our builder was able to buy the parts on Amazon and our electricians did an outstanding job installing them. They are perfect!

@mroy2606 - we used the same system and it works great. I actually had to buy a smaller width so I still have the 27" length if you want me to sell it to you at a discount.