There are many shops these days, selling cheap artists materials and these are great for children or if you are messing around but if you are a serious artist, they may not be of a high enough quality. It very much depends on the specific item, as some do not matter as much as others. A cheap brush can be massively different to an expensive one and the difference will show in the work. However, sometimes cheaper paper can be fine, depending on the type of work that you are doing on it but a watercolour painting, for example, will need to be on watercolour paper. However, if you are just experimenting with colours or styles then some cheaper artist materials could be worth getting.
Therefore it is well worth thinking hard, when you are buying these types of items as to what they are actually being used for. If they are for a very serious artist then they are likely to want the quality materials but for someone who is just starting out or a child, then the cheaper things are a great option for some experimental and fun work. That is not to say that you cannot save money on the more expensive brands. It is worth taking a look both at retail stores, art supply outlets and websites because you may find that there is quite a difference in price between them all, although the items they are selling is the same. It is worth spending quite a lot of time looking into this because you could end up being able to buy more items for your budget or saving money on the item that you wanted to buy.
Be careful though and make sure that you are comparing exactly the same item because the sizes may be different or the brands different, so look at the pictures and read the descriptions very carefully. You do not want to be disappointed with a smaller canvas or less paint than you had thought you ordered for example, if it is massively cheaper then this could be why. So look around really carefully and make sure that what you are buying is the best value for money that you can find and then you will guarantee that you will pleased with your purchase.