Two Nero Wolfe/Archie Goodwin books by Rex Stout are on sale at the same time right now, which is a bit unusual...
Black Orchids is early in the series, and includes two novellas,
Black Orchids and
Cordially Invited to Meet Death (apa
Invitation to Murder)
Kindle US, $1.99:
https://www.amazon.com/dp/B003T0G9HG
Kobo US, $1.99:
https://www.kobo.com/us/en/ebook/black-orchids-2
Kindle UK, £0.99:
https://www.amazon.co.uk/dp/B003T0G9HG
Kobo UK, £1.99, but discountable:
https://www.kobo.com/gb/en/ebook/black-orchids-2
Please Pass The Guilt is almost at the end of Rex Stout's Nero Wolfe/Archie Goodwin series
Kindle US, $1.99:
https://www.amazon.com/dp/B003V4BPUQ
Kobo US, $1.99:
https://www.kobo.com/us/en/ebook/please-pass-the-guilt
Kindle UK, £0.99:
https://www.amazon.co.uk/dp/B003V4BPUQ
Kobo UK, £1.99, but discountable:
https://www.kobo.com/gb/en/ebook/please-pass-the-guilt