There. Are. So. Many. Out. There.... it's no wonder women don't know where to start! The first piece of advise I can offer is there's no need to buy one before baby unless you're planning to exclusively pump and feed - if so skip to hospital grade motor pumps below.
These pumps are great for travel, ate easy to use, budget friendly and don't require power! They're usually harder to use, in terms of your hand strength, and take some skill/two pumps if you plan to tandem express. They're fine for the occasional pumping session (or the above) but not usually recommended to build supply (birth - 8weeks or if supply drops [very uncommon if excl. breastfeeding]).
SILICONE SUCTION COLLECTORS
These can be helpful for women with forceful let-downs to catch the additional milk from the opposite side. They are not recommended as your only pump, for exclusive pumping, long term or when you're aiming to build supply (birth - 8 weeks). They can cause areola swelling which can make it much harder for baby to latch/drain the breast and cause mastitis. They are very inexpensive and easy to use but can be frustrating if they're knocked off mid-feed.
ELECTRIC PUMPS (Standard motor)
These range greatly in price and functionality. Certain brands are very expensive for no added benefit so ask around. They're great for the odd pumping session, if you're out and about, are often small and compact and not usually too expensive (for most brands). They're not recommended for exclusive pumping or building supply (birth - approx. 8weeks).
ELECTRIC PUMPS (Hospital grade motor)
These are the gold standard of pumps and thankfully no longer an unobtainable price (the big ones from the hospital retail for around $4000 and used to be the only option). These are designed to increase/build supply in those early days, are designed for exclusive use and have good grunty motors. There are many amazing brands coming out now so ask around. Some have loads of parts to wash which can be off putting, some have all the features of the big hospital ones for a fraction of the cost.
Whilst I'm all for buying second hand, pumps are one thing to exercise caution with. There are very few pumps designed for multiple users (hygiene perspective) so at bare minimum look for a closed system (electric pumps only). This means the pump and milk can't mix because of valves.
Most pumps also don't recommend use beyond one year. The motors get tired and whilst they still work you may find they don't work as effectively. If you're needing to pump, you want it to be as effective as possible in the least amount of time as possible. Always ask when it was purchased, was it brand new to them, how often was it used I.e. daily, once a week etc. Also, always buy new valves or flanges for the pump as these are the most common thing to tire and cause ineffective suction. They should be replaced approx. every 3months if pumping regularly.
If you've got a brand in mind ask away, I've tried most out there/worked with them.
Kekoa's owner Alexis is a midwife and nutritionist and loves to help new parents navigate all that comes with parenting. She regularly presents new topics to help inform you, and always aims for a balanced approach.