There are essentially two ways to straighten teeth; using dental veneers or through correction using braces.
Having dental veneers fitted is a temporary fix using veneers which are just covers cemented in place that give the look of straight teeth to the naked eye. Braces are a much more permanent way is surgery which usually consists of braces of some type. This type of cosmetic dental treatment is performed by an as orthodontist.
The main type of straightening surgery performed is the fitting of braces, of which there are several different sorts; Standard braces are usually made of a non-magnetic metal and are fixed in place for the duration of the treatment, (often up to 2 years.) These metal braces are on the exterior of the teeth and are visible. Costs range from as little as £850 to just over £4,500, depending on extent of work and the type of braces used.
Invisible options include Lingual braces, which are fitted to the inside surface of the teeth and the Invisalign Brace, which is made from transparent material and fits over the teeth like a regular brace, but cannot be seen. Lingual braces are much more painful but can act much more quickly. The starting price for both of these treatments is £1,200.
Veneers can provide a way of giving the appearance of straightening teeth and could be more cost effective if there are few teeth to be straightened. Costs can range from £500 to £4,500 per tooth. Many foreign clinics now offer packages to travel and undergo the treatment advertising prices of £195 per tooth. Average prices in Budapest are said to be £150-£200 per tooth, (This can often include flights, transfers, temporary veneers and after care, but packages vary. Some may even include city breaks so you can sightsee at the same time. But is advised to be cautious when considering special offers and discount any silly offers altogether.)
One solution may be a custom moulded set of teeth that fit over your existing teeth to give the impression of the perfect smile. This comes in around £900, (including consultation and fitting.)
The cheapest way to get orthodontic treatment would be via the NHS. However, this is only available to children under 18 on dental health grounds (although it may be possible for some adults in exceptional cases). The NHS uses a system to assess the eligibility for orthodontic treatment which is called the Index of Orthodontic Treatment Need (IOTN), the Dental Health Component (DHC) of which has 5 grades, ranging from Grade 1, (almost perfection,) to Grade 5, (severe problems such as protruding teeth more than 9mm, chronic overcrowding). For the vast majority this leaves only the private option and prices can vary between practices and the types of treatment offered.