外國留學定是中國留學好呢？價錢如何？

You should consult education consultants for recommending suitable courses. Any person, including I myself, will just base on his/her past experience to offer you advices and in no way as accurate and comprehensive as those given by reliable consultants.

Nevertheless, I would like to offer you personal advices here.
If you just want to study English, of course you should go to UK and the total cost should be around $150,000 each year. Apart from those education consultants, the British Council should be able to offer you valuable advices free of charge.
If you want to study for a degree (but you need to get a higher diploma or equivalent qualification first), there are many choices. Several Chinese universities recruiting students recently including those in Canton. Their entrance requirements vary, depending on universities’ policies and academic status. The same applies to western universities. Therefore, my advice to you is to choose an university that match your academic standard and interest. After you get into the university, study hard and mix yourself with local people in some meaningful activities (e.g. participation in student union, perform voluntary work there. Never go to bars or you will just waste your money) will be the best thing you should do.

To study in mainland China, the cost should be lower than that in Hong Kong but will vary from one city to another. To study in western countries, UK should be a good choice but the cost will be much higher and may range from $150,000 to 250,000 depending on the course you study. A good alternative is to study in other European countries such as France, Germany, Norway, etc. Many of them do not charge school fees or just charge nominal fees.

If you are able to afford the costs, studying in western countries will enhance your vision.