A parakeet is any one of a large number of small to medium-sized species of parrot, in multiple genera, that generally have long tail feathers. Older spellings still sometimes encountered are paroquet or parquet. - Wikipedia
I think you would be very lucky to buy a parrot for £170. A quick search on Gumtree reveals prices of £300+ so I would be very wary of one being offered at £170 or £150 let alone £10, even if it had been living in a brothel.