Ideally, your tuba should last you not just a few years but a couple of decades. The materials, production processes and varnishes used in making instruments today ensure their long durability.
Apart from the production quality, clean intonation and a good response are important criteria in choosing your instrument. Many good beginner models are available at competitive prices. But you should always keep one thing in mind: Buy from a specialist dealer! Many producers have all parts of the instrument made by hand, and this comes with a higher price. Others outsource the production of certain components or buy components, such as the complete valve apparatus, from other manufacturers and assemble the parts by hand. Alternatively, the entire instrument can be produced industrially. Hand-made instruments, however, are said to be superior in finishing and quality.