Generic rubber handled spring barbell clips have an Amazon ship weight of 1.1 lbs. You could just use two sets of clips on each side, which would be 2.2 lbs. That's the only solution I can think of to keep you from buying plates, and you'll still be accurate to within 0.3 lbs, which isn't bad at all.
How much are you lifting? What lifts are you doing?
I use these $7 Cap spring clips from Amazon and have been perfectly happy (the most stress I put on them are 350 lb Deadlifts). If you're doing Olympic lifts with 500 lbs, you'll probably want something better.
That's a problem that five minutes on Amazon and $14 will fix.
You can get cheap albeit proper clips for a few dollars a set - don’t risk it with improvised stuff like that. https://www.amazon.com/CAP-Barbell-Olympic-2-Inch-Collars/dp/B000BJKWXK
My gym has this collars https://www.amazon.com/dp/B000BJKWXK?ref=emc_b_5_i are they heavy enough?