hello and welcome to ecf
vaping is all about personal preference so to be able to suggest something that would suit your needs we'd need to know a bit more

you already mentioned you don't care if it's discrete
there are a lot of choices
if you want something still small there are pods (similar to the vuse) that you could fill your own juice with....but you are still looking at cost of changing pods
then there are small mods with tanks or bigger mods
do you want a mod with a built in battery, these are nice as they still tend to be a bit smaller, however there is a life expectancy with these...once the internal battery dies the mod is useless
or there are external battery mods (you can still charge the batteries in the mod but usually suggest to use a battery charger instead) these can range from a small device (single battery) to a rather large device (dual, triple, quadruple (maybe) batteries) and the battery life is better than the above mentioned
then of course there are features lol vv/vw (variable voltage/variable wattage), tc (temperature control), squonk (a specific type of mod that has a built in bottle reservoir for juice, more for an intermediate/advanced user), mech (mechanical mod, not for a newbie unless you really read up on ohms laws and battery safety)
and then there is cylinder/pen style or box style shape
and of course vaping styles mtl (mouth to lung, probably more what you are used to) and dl (direct lung)
and of course there are different atties (atomizers) carts (cartridges), tanks, drippers....a tank is probably where you want to start with and of course there are drop-in coils or rebuildable tanks where you can replace the coil and wick yourself (you don't have to make your own, you can buy premade for cheap)
I know I'm putting a lot out there, just some food for thought
if wanting to save money then a rebuildable atomizer is going to be your better option but for starting out a drop-in coil tank is better, simpler, unless you feel comfortable to install your own coils (again you don't have to make them, you can buy them prebuilt for cheap)
just trying to help explain a bit more so you can be more informed before buying
all that said an good newbie starter kit would be the innokin kroma-a kit with zennith tank
other than that, the tried and true eleaf istick 30w with a protank or aerotank
things to keep in mind, the higher the mah the longer the battery will last
the lower the ohm of a coil, usually the hotter the vape will be and not all mods can run coils under 1ohm (sub ohm)