Choices, choices !! Its always hard knowing which one is the right machine, and then how long its going to last, will it be able to produce good coffee, etc. Unfortunately I cant speak to he quality or otherwiseof the Bes, but it seems like you have two options -
1. Keep it, learn to use it and work with it within its limitations, and get yourself a grinder ASAP (I think at least as much for the ability to adjust grind and dose as much as freshness, given once its ground its then impossible to adjust depending on humidity, age of the beans, etc).
2. Take it back, and keep saving while you keep an eye out for something second hand that gives you the quality you are seeking AND your price point.
I know it does sound so snobbish, but the grinder really is important. Its fundamental to the ability to get that 20-30mls of pure gold in the cup in 25-40secs of the pour; without the ability to adjust the grind you will very frequently end up with under or over extracted coffee, which wont do anything for your taste buds. To me this kind of defeats the reason for getting a coffee machine in the first place :-?
Perhaps some other options may be:
grinder plus stove top espresso / plunger / aeropress / etc while you look for and save for -
Second hand grinder / machine to budget when possible
I think another issue is that most people who truly get into coffee outgrow their Sunbeam / Breville / other thermoblock machines fairly quickly, and generally will replace them within 2 years due to mechanical issues, desire for better coffee, etc., so perhaps keeping an eye on the longer term goal whilst settling for the Bes now isnt such a bad thing either. Personally I dont like thermoblocks, and feel that they fit a price point for a time period, but are designed with a limited lifespan and are intended to be replaced reasonably regularly. In contrast a boiler machine (ie Lelit, Sylvia, etc) is designed to produce heat and be capable of sustaining it within the boiler without damage, so the lifespan will always be longer because it is more sturdily built, but also therefore more expensive.
Difficult choices really, and sorry if I havent done anything but confuse you more, but my one major piece of advice would be to consider that getting that grinder is probably more important than whatever particular machine you end up getting :)