The Italian side have offered 10million euros (£8.58m) for the Turkey international but Galatasaray value the 28-year-old at 13m euros (£11.16m).
The Turkish side's sporting director Bulent Tulun has arrived in Rome to open talks with Lazio officials and insists their valuation must be met.
Tulun told Lazialita.com: "This is the first official meeting with Lazio. For Yilmaz's move to Lazio, it is only a matter of money.
"Should the right offer arrive, he can leave Galatasaray."