The only SP-101s that come with a factory fiber optic front sights are the 4.2" versions in either .22LR or .357/.38 Sp with fully adjustable sights. I bought my .357 from a local gun shop several months ago and they had a number in stock. If that's what you are looking for, call around locally and see what you come up with.
If you want a fiber optic fromt sight on a fixed sight 2-1/16" or 3-1/16" pistol, Gemini Custom offers fiber optic front blades to replace the factory blade.