One of the myths and misconceptions out there is that you need an expensive tamper to pull good espresso shots. This couldn’t be further from the truth. An espresso tamper serves one main purpose, which is tamping or compacting the coffee tightly together as to ensure proper and even flow of water throughout the puck. Now, the most important feature of a tamper to ensure a quality tamp, is the base size. Water is lazy and it will always take the path of least resistant. A smaller diameter tamper, will only tamp part of the coffee but not all of it. This will cause the coffee that was tamped to be overextracted while the ring of coffee that was not tamped (due to the smaller diameter tamper base) to be underextracted. The mix of underextraction and overextraction will cause the flavor to be off. For under $30 you can find a perfect size tamper, depending on the size of your basket, that will last you a lifetime and will do the job perfectly (assuming you have the proper tamping technique down).
Many people believe that tamper weight is very important and they seek heavier tampers made out of stainless, metal, etc. but I personally disagree with that. As explained earlier, the size of the tamper is the most important feature of a tamper, weight is merely a preference as some people prefer a certain heft in their hand while tamping. Having said that, there is a case to be made for lighter tampers but that’s a different conversation for another day.
Having said that, many people will spend $200 on tampers, which is perfectly fine, but keep in mind that many of those tampers serve and do the same job the $30 tamper does. The main difference is that the $200 tamper most likely has a handle made out of fancy wood or exquisite materials with unmistakable craftsmanship (and other cosmetic attributes) while the $30 tamper is made out of metal or other plain more modest materials. The $200 tamper is most likely beautiful to look at but that’s about it. There is one exception to this however, some tampers that do cost $150 or more actually do a lot more than simply ensure a full tamp of the coffee puck. Tampers such as The Force Tamper, Bravo Tamper, Espro Calibrated Tamper etc. also ensure a perfectly leveled tamp as they sit on top of the basket ensuring that when the tamper base comes in contact with the coffee, it is fully leveled, this ensures that the water is (by sliding to the lower side of the puck) not going to prefer one side over the other. A sloping, uneven tamp can be seen from a bottomless portafilter if the coffee stream/cone is off center and can also be seen if using a double spout portafilter and coffee is coming out of one side of the spout more than the other. The Force Tamper will even go a step further than most tampers by applying the same tamping force, regardless of dose. This convenient feature is nice to have if you change dosage or coffees as you won’t need to adjust the travel distance of the tamper to ensure proper pressure.
To summarize, an expensive tamper won’t do a better job than a cheaper one if both tampers are appropriately sized for the coffee basket. The only time a more expensive tamper will do a better job if it can ensure a leveled tamp (by sitting on top of the coffee basket) and/or if it can ensure a consistent tamping pressure/force, shot after shot.