As a counterpoint, it is easy to spend more than $90 on a "dumb" lamp and bulb, depending on your style preferences and where you shop. There will always be a market for higher-end products.

Another way to look at this is Casper's business model. Casper mattresses are cheaper than equivalents sold at the likes of Mattress Firm (AFAIK), although not as inexpensive as IKEA. When you look at it this way, Casper's accessories (sheets, night stands, lamps) can be a way for them to sell complimentary products, at the same time they sell you a mattress, at a higher margin.