A father-in-law's birthday is a register problem more than a budget problem. Too cheap and it reads as an obligation discharged; too personal and it presumes a closeness that may take another decade to earn. ₹3,000 to ₹5,000 is the band where the gift is clearly considered without becoming an event, and the safest categories inside it are the ones that are useful to him without commenting on him.
Watches are the traditional answer and both of these are defensible. The Titan Karishma is the dressier of the two, with rose gold-toned markers and a date window at 6 o'clock, from a brand he will place instantly. The Casio Enticer is the more conservative choice — plain steel band, blue dial, and, importantly, a stated 50-metre water resistance where the Titan listing only says water-resistant. If you have no idea whether he showers with a watch on, that one specification is doing real work.
The Aristocrat Liberty set is the volume play: two hard-case bags, cabin plus medium check-in, eight wheels apiece and a three-year global warranty for ₹3,209. If he and your mother-in-law travel to see family more than a couple of times a year, this is the gift that gets used and mentioned.
The two air purifiers split cleanly on room size. Purocell is rated up to 180 sq ft — a bedroom or a study — and adds an activated carbon stage that handles cooking and traffic odours as well as particulates. FULMINARE claims up to 680 sq ft and a 24 dB sleep mode, which makes it the living-room answer. One caution: a purifier only helps if it is actually switched on, and some households find a machine humming all evening intrusive. If you have never seen a plug free in his living room, buy the watch.
This page runs five picks rather than a longer list. That is deliberate: every product here is one currently verified as live on Amazon India in this price range (the Casio lands at ₹2,993, just under the ₹3,000 floor), and padding the count with anything unverified would defeat the point.