J Lo claims love don't cost a thing, but Cardi B's proving otherwise by handing Offset keys to a very rare Lamborghini for his 29th birthday.

The "WAP" rapper blindfolded her hubby Monday night and slowly walked him over to his birthday gift ... a Lambo Aventador SVJ 63 Roadster. The sticker price is a whopping $600k. Keep in mind, Offset just gifted Cardi a new Rolls-Royce for her bday

One look at the bronze-ish Lambo and Offset was stunned -- and even speechless for a sec -- but it didn't take long for him to erupt in celebration once he got a closer look at the SVJ.

The initials stand for Super Veloce Jota -- Italian for super-fast, and the 63 is for the number of them Lambo made.
Prior to kicking off the festivities ... Cardi B took to Instagram to honor her hubby saying, "Happy birthday Hubs ❤️ I wish you many more."

She added, "Thank you soo much for helping me these past months getting my business in line (somebbody gotta be the mean 1 � ) I ❤️ u. Let's turn it up tonight!!"

Money deyt