I would second The Artificer's opinion. You really do get what you pay for with shoes; buy the best you can afford (I've heard it recommended that you should invest half your annual clothing budget in a pair), get to know the good brands (this is really the only way you will guarantee good leather unless you happen to be rich enough to visit Mr Cleverley or Mr Vass) and go to a shop to try them on as even with the same brand they will vary from shoe to shoe

Definitely go for leather soles: lighter, more elegant, breathable and repairable. I have pairs of shoes I invested in as a student which I have had repaired over the years and they still look magnificent. You will be saving money in the long run and will look good for years to come. A bad pair of shoes ruins even the best outfit.

If price really is an issue wait until the sales and shop judiciously: a lot of the shoemakers on Jermyn Street will have half price sales so you will get a good pair of shoes for a little bit over your budget. You will often find Loakes, similar to the styles you are looking at, in outlet type places (Clarks oddly enough) for £60 - £100 but someone like Trickers or Churches will give you a much more solid shoe.