I wont' bother recommending a shop, as my preference is KSS Altona and it would be a shameless plug.

But aside from shops. Look they are all 'good'. You need to know what you are buying. My advice is to try before you buy. Try the best brands and don't waste time with unknowns. Cabrinha, North, Slingshot are the top three IMO. North have a fantastic new range and their kites are considered one of the best made and well performing kites you will find. Bound to last you for years and hold their value.
Consider two kites if you are truly serious about it. A high over 25knot kite and one for 15 to 25 knots. If you want, a 2nd hand third kite for light winds would be great too. That's what I did and I am still using them all year round.
Forget 5thline and self inflatable kites. Stick with the norm and the well known and avoid 2nd hand kites older than 2009. Their safety systems are outdated and dangerous.
Good luck