Spider veins, Do I need to see a Dr. or can a "spa" inject saline solution to get rid of small purple veins on my legs? (photo)

From the picture shown, you have more than just spider veins and you also describe varicose veins.  Most likely you have underlying saphenous valvular reflux as the source of your veins.  Sclerotherapy may give you some improvement for a period of time, but most likely will not be long lasting.  You need to decide if it is worth spending the money on sclerotherapy which may not help or to at least have a venous ultrasound to see the status of the venous valves.

A medical spa with a physician overseeing the treatments is well suited to take care of these. Watch a video on my website from The Doctors showing foam sclerotherapy. However, if you have symptoms (aching, pain, heaviness, tiredness, fatigue in the legs, itching, cramping, throbbing of the legs, swelling of the ankles or legs), have the vein specialist do a venous Doppler study to determine if you have venous insufficiency. Treatments will be more successful if venous insufficiency is treated prior to getting sclerotherapy. You can also read my vein ebooks for free on my website to educate yourself about vein disease, venous insufficiency, etc.