We have discussed in general terms the pros and cons of using a free website template. In their favour, is of course the excellent price :-) But consider some of the common pitfalls you may encounter before deciding to use a free template. Note: these are possible, generalised problems you may encounter. Not all free templates exhibit any or all of these problems, so make your decision on a case-by-case basis.
Restrictions
Most free website templates are restricted in terms of usage. You may need to credit the original designer (you probably should anyway, after all he/she is providing his/her work for free), and you will usually have to link back to the designer's website. Consider all relevant restrictions carefully before deciding to use a free template.
No or limited support
In many cases, template designers are not prepared to support their free templates. This is unfortunate, and many designers will provide some support for free website templates, but keep this in mind. You will be better off when you use a free template, if you have some experience in using templates to create websites.
Not professional
This is not always the case. However, the templates a designer offers for free are often not their best work. In many cases, they are not even the work of a professional website designer (who expects to be paid for what she/he produces). You may find that the free template you choose is badly coded, doesn't display well in all browsers, or is difficult to edit.
Over-used
Naturally, free website templates will be downloaded and used to create websites more often than purchased website templates. You are more likely to encounter another website that looks identical to yours if you use a free template without modifications.
You will find professional website templates (both free and paid-for) here.