I bought Shimano 520s and M064 shoes because that was less than £80.00 online. The shoes are mountain bike shoes so I can walk around in them easily, road shoes are a cycling only footwear. You can get the exact same new off of ebay on Buy It Now for £65.00 or so, that's shoes and pedals.
I feel very safe and secure in them and i think there's a power benefit but not able to prove that. I was nervous at first but then thought "what's the worst that can happen?" (Almost found out today!)
Buy some and get on with it, if you need help with cleat fitting there's plenty of stuff online about how critical setup is but with Shimano 520 there's plenty of give so I just cracked on and no pain or discomfort. I'm far from an expert but here to give a view when/if you want one.