Yes you can replace the rubber boots only. Go to Auto Ricambi and they are $4.70 each for the ones I bought this month. I replaced the ones on a 81 spider I bought last year with 48,000 on it with bad boots and good tie rods. You can also get boots for the ball joints but I don't remember where right now.
Good luck and enjoy!
1987 Lotus Super 7 clone
1981 Fiat Spider 2000 AT
1982 Fiat Spider 2000 5sd
1970 Fiat Coupe