I want to grow lemon and coffee trees indoor in winter and outdoor in summer in PNW climate.
What variaties will work better for this purpose and where to buy them?
I've purchased a lot of plants from Forest Farm in Oregon over the years and have always been pleased with the service. I'm guessing they'd have lemon varieties, but not sure about the coffee .......
Ditto nice stock from Forest Farms. Raintree edible landscaping (Morton) has the lemon, probably not the coffee.
I bought my own coffee plant at an Ace Hardware - at about 5', it resides under a skylight at the end of a bathroom :) If convenient to their location, you might try someplace with a variety of houseplants, like Molbaks (Woodinville). If you live farther south, possibly Tsugawa's (Woodland)
Here is a link that might be useful: Raintree Edibles